Developed nations give them enough money to pay rent after they retire.

Because you know, they shouldn’t have to work in order to live when they can’t anymore.

An answer to your questions in order:

Yes. At the point where an owner can easily afford to lose that building as a tax write-off. Yes, if their own wellbeing isn’t dependent on that property, with a reasonable compensation for their loss. She was there first.

It may not be the right answer, but it is one.

1. Yes
2. Ideally from birth
3. If they’re wealthy enough, yes. Or ideally, people who can’t afford a home should be given one by the government. No landlords needed. Having a roof over your head should be a basic human right.
4. Nothing. Again, basic human right. Everyone is entitled to a home.

It’s just especially sad and cruel, in reality housing should be decommodified.

You’re begging the question that the squatter is the recipient of charity, and not the landlord.