First case, and why does the onus fall on the owner to disprove that they tried to contact them or didn’t give them permission, and then they have to fight for how long in court when they want to use that property that they paid for? As soon as the owner returns and notifies the squatter, they should have to leave. They’ve been informed that it belongs to someone, and because they never in any way earned, traded for, built, or acquired the resources for it, therefore they lose any rights over it. Their free rent for however long they were there is just the luck of someone else not paying attention.

But the idea that the legitimate owner now has to fight someone in a court system that will cost literally 10s of thousands maybe 100s in money and cost years of their life while they pay taxes and continued costs of the property while someone who simply

took it will live in it for free is, frankly, ridiculous.

Your second case isn’t a property rights issue because nobody owns it. The govt is simply failing to account for a dead owner - that’s a clerical issue easily sorted when every bill ceases to get paid. If the govt wants to donate it to a squatter, then by all means. The govt had no legitimate right to it either, squatters rights win.