MP's expenses... a privilege to far?

I was a local government officer (a public servant) for quite some number of years, both in London and the home counties. In order to claim expenses, I had to provide receipts for every penny I spent in connection with my work. I had to submit these expenses to my line manager for approval by the beginning of each month or risk a long wait for reimbursement. Each claim and each receipt was checked again before payment was agreed. Any problems and the claim was returned unpaid. Why is it that MP's, who are also public servants, are not required to submit receipts for every penny they make a claim for? It is public money they are taking. Why is it that MP's, who are public servants, are so privileged that they can abuse the public purse in any way they like? If not abuse, then stretch the rules into the realms of fantasy, or do I mean porn and dodgy second homes. Whatever, it is still public money they are taking. MP's are supposed to have standing in society and are meant to be looked up to by lesser mortals. What with one MP falling after another, this of course has been proved to be an illusion, to be a confidence trick. Privilege of course, comes with standing. You can see it at every level of society. It goes with the job. It is a reward for upholding certain standards that the Establishment approves of. You can see it everywhere; the policeman, the social worker, the magistrate, the judge, the county councillor, the local councillor, the teacher, your GP, your MP. What's gone wrong then?  Nothing, it has always been that way. It's just easier to uncover bad practice and deceit these days thanks to the erosion of deference (doffing your hat to one's superior) and investigative journalism. Perhaps I will get one of those blue front door stickers that says; No Hawkers, No Cold Calls and add to it... NO MP's. 

! Note. I am aware that I am generalising here and recognise that not everyone should be tarred with the same brush.