There's roughly a 25% chance the credit card reader / app will incorrectly reject payment (broken or not) on competitors' stations, and roughly a 10% chance the charger will be broken. There's a 1% chance it'll feed bad voltage to your car. There's also a 5% chance you'll have to make a phone call to arrange payment.

Of the dozens of issues that I've had across a few different cities, I think the problem was related to the connector once.

If they'd simply put standard vending machine credit card readers on them and not bothered with apps, they'd have cut their downtime by at least 75%.