Of all the thousands of things I own, as far as I know, only my car and my house exist in anyone else's ledger as belonging to me. Am I missing something?

I would find that hard to believe. You have a bank account, surely. A life insurance policy? Airline points? An account with the government social security office for your pension? There are probably dozens (if not hundreds) of things of value (even if the value is near zero) that exist in someone else's ledger.

All of your property exists in a kind of implicit ledger that a court can reify when needed. If a court decides your bed isn't yours, then it isn't.

Your 401K. Your brokerage account. Your bank accounts.

Your phone will show up as yours in some Google or Apple database.

Your credit/debit cards (really your credit card accounts) will show up as yours in some bank database.

Your laptop may show up as your in some Apple/Microsoft/Google account.

The money in your bank account?