It was sort of a joke, I’m mostly just not used to it - but also apparently it’s a pain if you forget to do it.

You have to log into a website and enter your point of exit. That way whatever was subtracted form your credit can be returned to you.

It’s the same for train travel. It is an honor system because there is no way to check if that really was your exit or not.

In London it is a slight benefit to poor people with lots of time, as you can travel a long way (sometimes) on a single bus.

But the Netherlands has a country-wide system (unlike Britain) so it has this compromise of tapping out.