I'm a wedding photographer and there's a lot more to wedding photography than turning up with some big camera and clicking off a few shots.
We charge what some people might consider highway robbery but we use the best equipment, are fully insured, look after our couples extremely well and produce shots that we are proud of from every wedding.
You also have to remember most weddings are on the weekends, they're long demanding days and mostly during the summer months with not much during the winter. So there's only a finite amount of working days in the year in which you can make a living. You then have to take in to account travel costs, food as well as the small things that add up like parking fees etc.
Also you need to sort, process and work on each image after the wedding. Design an album, with multiple requested changes. Couples invariably come back with certain images they want in black and white or little things done which saps away time but that's part of good service although it does eat in to profit.
If paying for a professional isn't your thing then you can great memories from putting a laptop at your wedding with a card reader attached and asking everyone to download their pictures before they leave.
It's all down to what you want in the end, we have never had an unhappy customer and no one has ever begrudged paying us the money for what we do. In fact we are now friends with some couples we have shot for.
I think there's a lot of people doing £500 weddings because it sounds like a lot of money for someone with a DSLR and a lens to be making for a days work. Unfortunatley they can take pics all day, run them through photoshop quickly, erasing the ones that came out terribly (for a non pro at a wedding probably 4 out of 5 shots would most likely be chucked rather than 1 out of 30). They then hand them over on a blank dvd in a plastic sleeve and think about what to spend all that profit on.
No wonder people question why they get no better than uncle bob with his camera because it's virtually the same apart from you're paying someone elses uncle
If people care about their photos then they will hopefully see why wedding photographers who produce results and really care cost so much.