They often avoided having to fight in wars too ;) On a more serious note, in the past nobility and clergy were often exempt from various taxes (e.g. the taille,

They often avoided having to fight in wars too ;) On a more serious note, in the past nobility and clergy were often exempt from various taxes (e.g. the taille, the main tax in Ancien Regime France) because of the other "value" they were bringing to society - an argument not dissimilar from those we hear today against various kinds of wealth/capital gains taxes!