A small fee to use a service will get rid of fake identities and bots. The answer is charging a fair fee. Not scanning iris’ to track that every person only has one account.
In that case you are simply delegating indentity checks to credit cards companies / banks. Earning money independently is definitely within the reach of current AI models.
No, it'll get rid of bots worth less than the account fee to run, except for people who can do payment fraud.
It won't get rid of fake identities because you have to do identity verification for that; otherwise you can impersonate a corporation.