What if their house straddles the border, and they work from home? Are they not allowed to have their computer in one side of the house? Who monitors this?
Technically they would probably have to be dual citizens, or a citizen of one country and permanent resident of the other, to not break laws. And then they'd have to file taxes in both countries.
No idea if it's enforced, but if it were, it would probably be such a pain that people would just stop buying/building houses that straddle the border. Why complicate things unnecessarily with a house split between two countries when you can just buy a house that is (like most houses) entirely in one country?
Not at all true, it sounds like you're just guessing about what how you think things should work?
> And then they'd have to file taxes in both countries.
Not at all true again, regardless of where your house is, even if you're a dual citizen. The US is the only country that claims to be able to tax the earnings of its citizens outside of its borders.