Once they figure it out, they can come back as a paying customer. :)

It's not the provider's responsibility to help their customer get their sh#t together.

You typically get multiple reminders. If that's "an error", then that's an error that will happen again and again and again.

That's a problematic customer you don't want unless you're otherwise broke or want to keep them for other reasons (e.g. publicity).

You'd lose out on headaches from your customer not paying and having to waste resources following up on it.

If they can pay, then just pay for the service they got.

Seems pretty straightforward.

> It sounds more like a error

It seems like Mozilla has made quite a lot of errors in the past few years.