Are every single wallets passwords useless once someone have access to the private key or recovery seed? Are there no projects or chains that implements password inside the private key so that even if you import the private key in a another fresh wallet you will still be asked for the password.
I will talk here about non-custodial wallets, since custodial ones are simply accounts on a platform, not proper wallets.
You should start with understanding that the coins are not in the wallet, they're on the blockchain. Anybody who can sign a transaction he can send away the coins, that all that's needed.
You should also understand that usually you have a wallet software and a wallet file. The wallet file contains some information that allows the wallet software obtain the private keys necessary to sign transactions.
Now, if you protect by any means (password) your wallet, it's basically only that file you protect.
One can make from seed/private key a new wallet file and sign transaction. One can use the private key with a script and sign transaction (i.e. spend those coins).
So if you have password for your wallet, but you don't protect the seed/private key properly, it's like you put a steel grid over your window, but keep all the doors wide open.