I get like 3% a year on my bank (gotta get my new card I remember now), anyway....
Most of the time you're getting money if you got money on it.. If you're in the red (-), pay it back as quick as possible. They're indeed getting more money from it then indeed, you can't do shit about it :redface:. Also keep in mind that a Mastercard is more expensive then a regular Maestro (no idea what they have in there), a normal price (mine) is about 40 euro's a year to use my card totally (yeah, got a Mastercard --').
I'm with Credit Agricole and the ING (which I lost the card from, probably now somewhere in the North Sea.
All in 1 : Try get a prepaid one.. Mastercard (mine isn't in here, I've can go red until 50, which never happened yet) has to many risks in here.. There's not big difference expect the fact you can not pay in America or either Australia. Shame.