"a pro is someone who has started to make money out of his equipment. Be it 1 cent or a thousand dollars" Quoted from Mr Yim Chee Peng.
I think the amount set is purely justifiable by the person setting the amount. I'm far from turning professional in the area of photography. But i understand the logic of wanting more cash to upgrade and maintain equipment, to give myself a better living and perhaps to contribute to my family. Good photos are subjective to the individual. so wat defines good and bad now? U get what you pay for. But it doesnt mean that high end photographers will definately charge a minimum flat rate. I have came across ppl whom because the couple really appreciate his work but cannot from the bottom of their hearts afford to have a photographer, decide on doing it for a fee the couple is comfortable with. But this doesn't mean he will do it all the time.
Hope i'm not talking a whole load of crap. just sharing my simplistic point of view.