It’s this way because of how regulated everything is. You have to jump through hoops to get permission to do anything here in the U.S. in other countries you just do it.
In my city it’s pretty deregulated. But there are downsides. Sloppy techs will cut competitor cables due to pure laziness.
Once it is up, the regulations will work for you. Some day, some other "legit" installer will come by and look at the cable and basically shrug their shoulders at it, and then do their work around it. It would take weeks if not longer to find out nobody knows who owns it. Nobody's going to take the time to trace it back. And I'm guessing nobody is going to just take it down for fear of taking the wrong thing down. Maybe they cut the line and wait around to see who comes to splice it?? It would make for an entertaining story.
I can't pull them up now, but I've seen a number of credible stories on the internet of Comcast and AT&T technicians going to homes to do service and then intentionally cutting lines of the other company that service the building or nearby houses. Obviously this isn't super common or it would be bigger news, but it definitely happens.
It's a big deal to damage someone elses infrastructure, can result in bills and lawsuit to reclaim losses. If the pole owner notices, they may do something (or just ignore it). What you don't want is them tearing down your stuff without notice.