It even exists now, if you mis-send USDC/USDT you can petition Circle or Tether to reverse or change a balance. Commonly required when sending USD* to an address that can't move it out or handle it.
But ALSO a lot of payment systems that people like are in fact not reversible, even by courts. And people like them that way - it prevents fraud. Fedwires, Swift wires. Consider selling a high value item: there are few ways of electronically transferring amounts that can't be frauded out later. This is why many used car sales are done via cash - can't undo cash!
If there is some shenanigans going on then the buyer/seller can just take it to a court. Cash or not isn’t really relevant to the legality of a transaction it’s just a means of payment.
It’s just like the deed to a house, it’s not really relevant to the purchase of a house. It’s that the buyer and seller respects the legal framework surrounding the transfer. A blockchain storing house ownerships doesn’t add much?
what about your bank account?
There is nothing wrong with having public immutable ledgers making tampering visible. This is useful. But the question there is: what is the drawback of centralized ledgers, e.g like the ones for interbank transfers? Even git a git repo represents a kind of public ledger like that.