I have an electric car charging account with chargepoint. They see how much usage you have and predictively fund your balance periodically.

When I first used it, I wouldn't use very much and I would get notices from time to time that $10 was added to my account. When my usage went up, they did $20 for a while, and at one point I hit $50.

I think this is reasonable and if it makes the overall cost of a service lower I am all for it.