You can cryptographically prove ownership, that’s the base over here. With that you can verify your identity by linking it to a domain you control via NIP05 https://github.com/nostr-protocol/nips/blob/master/05.md
In the end the whole system here is math based, over there it’s build on top of authority.
Payed relays also give scamming and impersonating a cost, so there is less financial incentive to do it.