You're fundamentally trying to transfer your money to the operator of the charger, but they aren't standing around to give cash to, so you want something digital. Alright, so your bank should do this -- you authorize your car's private key to make withdrawals from your bank account at charging points and we're all set. Except that banks suck at this sort of thing, which is why we have the credit/debit network to create some kind of standard. Except the standard is credit cards, not public key cryptography.

You wanted to give your money to the charging point operator but instead you have to give it to your bank to give it to Visa to give it to the charging point operator. Now we're going to add "Tesla/whatever" to the chain? This needs to stop. You stick with the card reader until you figure out how to get banks, using some kind of standard, to support the public/private key thing and we can remove a middle man instead of adding one.