At no time in history have national borders ever been a universally shared reality and frankly, they could only be such by coincidence, not as a reflection of any genuine physical state of affairs beyond the state of mind of every human on earth.
No one is saying that those boundaries cannot change in the future or that if history had been different then today's boundaries might be different.
At the level of political science, most people understand international relations to be, more or less, a sort of state of anarchy, where boundaries are nothing but a bare reflection of power. From this point of view, most calls for "agreement" about a disputed boundary are nothing more than demands by one party for the other to accede to their claim of what they own. I personally believe that this kind of bickering by nation states is pretty far beneath the dignity of the label of "real" and all human beings would be better off if we appreciated that fact.
It seems like you are getting hung up on the idea that "real" means that something can be proven using physical laws. For most people in most circumstances, that's not a particularly useful way of defining real. Usually, "real" is defined as something like "the facts on the ground that impact our lives".
Take for example, Taiwan. The facts that people mean when they talk about Taiwan's borders being real are something like: Taiwan's status is in dispute between China and most of the rest of the world. In order to maintain diplomatic relations and prevent war, most of the world has adopted a policy of officially ignoring the dispute while unofficially supporting Taiwan's independence. In terms of day to day governance, Taiwan is independent from China. For example, the reality of the Taiwanese border is that there is a dispute between China and most of the rest
But that's exactly what they do already, when allowed to.
Have a look at Jammu Kashmir. If you're not located in India or Pakistan, the disputed borders are shown as dotted lines rather than the normal solid lines for national borders. If you look at the details of any location in the region (e.g. the city of Jammu), it won't show any country.
Now, if you're in India, it'll not display any disputed borders and instead show the entire area being a part of India. But showing the dotted line isn't an option, showing these borders is required by the local laws. And you wouldn't want a multinational company to try to flout the laws of the countries they're operating in, would you?
There are far far more contemporary examples of nations agreeing on where the boundaries are than examples of them not agreeing. The status quos is generally agreement.
No credit for saying “all signs of humans beings vanish”, the same logic applied to biology would suggest that life was a social construct, as if all signs of life were removed, there'd be no evidence of life.
My primary point is that this trend seems to be accelerating from my perspective so it's fitting for online maps to reflect this as well.
No, we all operate in the same reality no matter what. That is kind of what "reality" is - the set of physical facts which obtain regardless of our particular state of mind or coordinate system, local velocity, etc. The idea that we should elevate some subjective opinions to the level of reality that we expect everyone to share is actually really damaging to the idea of truth and objective reality.
No doubt accidentally, you're advocating for a subjective notion of what is real, not an objective one.
No one is saying that different people are subject to different natural laws. Nor is anyone saying that certain perceptions or interpretations of the world should be elevated to the level of natural laws.
I don't dispute the utility of shared social conventions and rules. They are very handy, no doubt. But they aren't reality, and, in my experience, the people most vociferously asserting that they are are the jerks.
If two nation states _agree_ on a border because it simplifies administration, then bravo. If two nation states disagree about a border then the problem isn't that one has lost touch with reality. The problem is just a dispute about power and suggesting its a problem with perception of reality is propaganda. At a fundamental level borders aren't real. If there is a conflict over them, the only recourse is to the human beings involved, hopefully through diplomacy, but unfortunately often through violence, but never via an objective process which reveals by experimental or theoretical action an objective truth.
Confusion between that which is real and that which is not is the deepest, most destructive of intellectual maladies.
As a concrete example, many conservatives in the United States understand border control in terms of national security, sovereignty, cultural integrity, etc. They often do not understand the interpretations that advocates of open borders base their views upon; things like viewing freedom of movement as an inherent human right, seeing borders as a way that corporations undermine labor, seeing Mexicans as having historically inhabited the American South West, etc. As a result, those conservatives misinterpret advocates of open borders as unpatriotic, attempting to undermine America's sovereignty, attempting to replace their culture, etc.
Basically, the issue isn't the disagreement, it's lacking the shared understanding of the situation that would allow discussion of the disagreement.
The borders of plots of land are frequently disputed. There are plenty of places in the US where two or more deeds define overlapping properties (which should obviously never be the case, but here we are!).
Country borders are no different, and it's unsurprising that they very frequently disagree. The US and Canada have disputed territory, even. To suggest that borders are "real" in any sense implies that there's one correct, canonical set of boundaries. But there's not and never has been. There's no singular authority that decides what the borders should be. Wars are literally being fought right now over borders.
A border is, in comparison, next to nothing. Transient in time and nearly meaningless in space. Surely of consequence to human beings but only via other human beings. Indeed, the very fact that armed men are willing to kill for the transgression of such a pitiful thing is a brutal absurdity which does little to recommend us as a species.
Armed men and brutality suck but if you think of countries as living beings (eg. country as anthill and citizens as ants, or country as human and citizen as cell/neuron) then it is kinda understandable.
End of the day everyone has a 3 inch chimp brain. Its not designed for common reality.
2 brains growing in same environments, exposed to the same things through their live can turn out to have totally different beliefs. And thats just looking at my own family members.
Its like planting 2 seeds in the same soil, giving them the same sun and water dont produce the same exact number of leaves, flowers or fruits.