That's only for trains. For bus/metro/tram you only need 4 EUR on your card. See https://www.ov-chipkaart.nl/reizen/tarieven/instapenbasistar....

If you don't want to use your card any more you can get the money back, though. Minus a 2,50 administration fee, of course.

Can I get the 7.50 I was forced to pay for the card back too?

Don't think so.

Other than the obvious money-grab by the authority (1 million cards x 20 EUR x 1% / 12 months == 16666 EUR income each month), what's the reasoning behind this? Only financially solvent individuals can use public transport?

> what's the reasoning behind this?

Fair, per-kilometer pricing. Quoting from the english version of the page linked above[0]:

  When you travel on credit, a boarding fare will be debited from your card when you
  check in. When you check out, the boarding fare will be refunded and you will be 
  charged for the number of kilometres you travelled. If you do not check out, you
  will pay the full boarding fare.

Not everything that looks like a blatant money grab is one. Hanlon's Razor[1] prevails once again.

[0] https://www.ov-chipkaart.nl/reizen/tarieven/instapenbasistar...

[1] http://en.wikipedia.org/wiki/Hanlon's_razor

It probably deducts the max fare when you tap on, and then refunds the difference when you tap off. The max fare must be 20 EUR.

Caltrain works like this too, though the card will go $5 negative, so you need max fare - $5 on the card at all times.

I'm assuming they have variable pricing based on distance traveled, and 20 EUR covers the highest fare for the system. That could just be my optimistic bias speaking though.