[edent]

> Ownership of a blockchain address can be proven with a signature.

How? If my friend gives me their passcode / phone / Token, I can impersonate them.

[arbol]

Maybe this is ok. The reputation of the account is still at stake and the friend may have trusted you with their private keys so that you can give taxi rides and increase the overall account reputation.

If the private keys were stolen then a malicious person could impersonate your friend and act badly. Similarly, in the current system, a person can pretend to be a taxi driver and act badly.