I think most of our disagreement is about the word
ownership. I think many of the times you've used that word, it would be more accurate to say
possession.
Your car example is a good one. If somebody has your keys (either with permission or stolen) and they take your car, they have possession of it but at no point do they own it.
Another example - lots of companies have crypto wallets and own Bitcoin and other currencies. Corporate wallets are controlled by agents of that company. The people who know the keys don't own the crypto, the company does. If an employee transfers from a company owned wallet that they control to a wallet they own, that's theft the same as if they had wired money to an overseas account of theirs.
Possession and ownership can align, but they don't have to. Smart contracts can be legally binding, but that isn't guaranteed. None of this exists outside of our legal system.