Lad you said in your thread about your lakeland dog ,that your father rears pheasents,so i reckon you should well know why foxes need controlling.
digging them is one of the most productive and humane ways of control ,they have no natural predators in the wild so in order to keep their numbers down man has to intervene.
look at the urban fox population ,9 out of 10 of them are mangey skinny specimens because they have no way of proper control on them.
the reason most of us do it is control and also enjoy seen working animals doing what they where bred for(look up the meaning of the w