It's not just BP.
I just used Fastned for the first time a few days ago and was annoyed to find that they do a £40 pre-authorisation. A bit of a pain for someone with a 30kWh Leaf which could only ever take about 25kWh at 40p/kWh which is £10. Yes they did cancel the pre-auth afterwards but if you had less than £40 in the account to begin with the session would have failed.
As noted Instavolt also pre-auth £15 if you use contactless.
Kind of annoying that you can roll up to any petrol station and fill your car up with (depending on tank size) nearly £100 worth of fuel without even proving that you have any sort of payment method at all, and only if it turns out you don't is there a problem.
Yet charging an EV you have to prove that you have many times more money in your account than the likely cost of the bill.
And for those companies that actually take the money and don't refund the difference for several days, (vs a pre-auth) shame on you. This is not legally defensible IMO. You are literally taking and sitting on money for services not rendered.
This can sometimes even happen with a pre-auth that doesn't get cancelled for a long time, and I have had it happen to me with instavolt before where the pre-auth was not cancelled for a number of days after using the charger, (it only ever showed up as pending during those several days, not as taken and later the difference being refunded as it sounds like here) this puts a hold on the money in your account so might as well be them taking the money then refunding it later from the point of view of having less money available in your account.