You're getting at the root of the problem here, which is that Visa doesn't actually support anything like that and "whatever" is going to add another grubby middle man to the transaction, which is the thing that most needs to be prevented.

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.

Visa et al are going to charge a minimum transaction fee for small-value transactions, which covers the typical charging session. Third party services are an advantage, because they can bundle small transactions together and take advantage of their economies of scale and their own fraud models. There is a world where Visa and the payment card industry looked forward in the year 2005 and said “IoT devices like EVs will need payment capability, let’s think about how to be essential to this ecosystem in a way that removes the need for third party services and saves everyone money” but that kind of technical innovation seems to be outside of their core competency.

The transactions are of higher value than many public transport tickets, and those are already common — either as normal purchases from a ticket machine, or with the special transaction type used when the payment card is touched to the reader on the ticket barrier.

Following a recent trip I had a bunch of ~1€ transactions from buying single bus/metro tickets from machines.

Visa charges a 5-10 cent fixed fee plus a percentage for those 1 Euro transactions. Presumably public transport just eats those costs, but in a commodity business like electricity I imagine it’s a noticeable chunk of the profit margin.

1 cent fixed fee + percentage seems to be the standard where I am. It might be difficult in other EU countries but IIRC the fixed fee is capped at 5cents.

The only public information I can find is this, which is from 2013 in London:

Visa credit 0.65%, debit 1 pence. Mastercard credit 0.80%, debit 1 pence + 0.5%.

https://www.whatdotheyknow.com/request/costs_to_tfl_for_cont...

> of ~1€ transactions

In Europe, sure because the fees are capped. In the US you pay a fixed fee + x% which makes small transactions like this prohibitively expensive

I agree, except Visa and Mastercard are willing to innovate. Apple Pay/Google Wallet for cars isn’t an unrealistic goal.