The point is that we don't know for sure if the original owner lost the keys completely or just one copy thereof. It's not like physical cash, which if unclaimed can be reasonably assumed to be lost after a certain period of time.
I don't know what you would do in case you lost your seed words, but I sure won't carry them with me in y pocket or wallet everywhere I walk.
Even if I somehow lose them I would notice this and use backup option to recover and send my coins to wallet I control, but I would do this the same day or few days after.
It's not like I would wait weeks or months to recover my coins, and it's always possible he never created any additional backup, that is expected from someone who carries seed words with them.
My main concern would be how to monetise the btc without having to give 30% to the tax man.
Government parasites can't charge you any tax for something they don't know you (temporary) own... just sayin, I am not your tax advisor.
We have similar laws: it just means that when you find something, it's not automatically yours. I think there's a 1 year time limit here for the owner to show up.
I think many of the laws are not working in real life, especially stuff coming out recently.
I mean they are trying to legalize taking away land from farmers, and if that is not some new communism I don't know what is.
Pay taxes, obey the law, and don't think with your head.