The trick is simply to ensure you pick a government that isn't going to pass that kind of invasive legislation, or will remove it and retrospectively revoke all access granted under the legislation that they're repealing.
As for Great Firewall of USA, what makes you think it doesn't exist already?
Privatizing publicly built infrastructure did not inoculate us from surveillance.
To actually do it we need to exercise control through the collective mechanism we call government. Laws, regulation, oversight, audits, sunshine policies. It's the only way to curb it. Mistrusting your only mechanism of control and putting blind faith into private markets did not work. We tried it. It failed.
The actual problem is the centralization, regardless of whether it's public or private. There shouldn't be two ISP options, there should be a thousand, so that anyone wanting to compromise all the traffic has to compromise a thousand independent entities, some of which can then be operated by stubborn curmudgeons who would rather loudly go to jail than silently betray the public.
A. Break up the companies, assume mergers and acquisitions don't happen, consolidations never happens and that someone will be defiant of the law in the public interest at a crucial point
B. Change the law
It's important to note that AT&T was broken up and there once was many mobile carriers and there were many surveillance and spy programs going on during that time unabated and then they just bought each other up.
So instead of wishing on a hope and a dream that some invisible hands will orchestrate unexplainable market magic, let's just change the law. There's actual historical evidence of that working.
Or just prohibit them. That's a change to the law you can actually see is being enforced.
The problem with changing the spying law is that the spying is happening in secret, so there is no way to verify that they're not lying to you as they have in the past. Laws with no accountability mechanism are a farce. They need to be backstopped by verifiable structural inhibitions on the practice, like diverse decentralized infrastructure subject to competitive pressure and plausible independent reimplementation by anyone who doesn't trust the incumbents.
> someone will be defiant of the law in the public interest at a crucial point
This is required to turn back injustice. But it's more likely to be achieved the more people have the opportunity to do it.
For the smallest issues, you can expect a single bundle to already have spare connections. For bigger issues, almost anything that takes out one bundle will take out the neighbors too.
Meanwhile diverse ISPs wouldn't be using the same A and B. ISP A has a central office in a high rise downtown, ISP B primarily targets single family homes and has their switching equipment on a piece of land next to a substation in suburbia, so if you subscribe to both you not only have links coming from opposite directions, they're each operated by independent organizations instead of a monoculture.
In the last decade a number of ISPs have popped up and decided to fibre up areas. They are invariably buying OLTs from Nokia or Adtran (the same two vendors as BT OR) putting them in a BT OR exchange because that is cheap and very convenient, good access to backhaul etc and then renting BT OR ducts and poles to install the fibre in/on (PIA). To top it off they often are using the same fibre vendor as BT and sometimes even the same contractors to install it. Worked example of this; netomia/youfibre (though there are dozens).
What resilience are we really gaining here? Organisational, and that's pretty much it.
Now suppose that anyone could run an ISP out of their house. They wire up a few of their neighbors and then make a single long-distance run to one of many backhaul providers, none of which has a dominant market position like BT. The backhaul providers connect to their customers and each other in telco hotels, but they're smaller and more numerous because each of the largest providers has their own, so the city has three or four instead of one.
Meanwhile even if you have a BT, organizational independence in itself is better than nothing.
It is a fine concept but you'd have to actually ban infrastructure sharing between ISPs and be building a completely Greenfield network. Quite theoretical. I'm aware of former eastern bloc countries that have dynamics somewhat reminiscent of what you describe though.
You could require them to provide those services for their competitors at regulated rates, but then you're not actually breaking that monopoly, you're just regulating it while cementing it in place.
If you have an existing monopolist then first you have to thoroughly break them up, not just mitigate the continued existence of the monopoly.
Ensuring there isn't a single point of failure is not just as simple as 'putting it in the contract.' Carriers can and have groomed their primary and backup circuit on to the same L1 path without realizing it.
I've never seen it happen in 20 years. Although of course small parts of the path change over time and sometimes that means bits get put in the same duct for a short run but that also happens when you buy from different providers to be honest. With some carriers you can insist they send you updated route kmls when they change either path and you can detect the change as you'll see different losses/otdr traces before and after a maintenance/fix.
Most of the country has more than one physical fibre (or FTTB/FTTC/CATV) provider available.