MPs may earn more than the national average, but they don't earn anywhere near enough money to pay £6000 a month tax.
I will agree that few people can do nothing all day and earn alot of money. However, my experience is that people who earn very large amounts of money earn the money because they are motivated by having lots of money. A research scientist trying to find a cure for cancer will earn less money than a really successful car salesman although both may work really long hours. Doctors do in general earn fairly large amounts of money, but not as much as city traders. Do we really, really need city traders more than doctors?
Somebody paying £6000 a month in tax still has an enormous amount of money left over.
(think all I've done is rephrase what capp said)
The only thing I will give the OP is that I think most parents would pretty much do anything to help their child, and there is probably no amount of money that would be enough to help a very sick or disabled child, so on an emotional level, I perhaps have sympathy for her. I will also agree that it might be frustrating if she felt her tax money were badly spent.
However, in terms of the taxation level in general, I do not think a city trader needs another car more than a mother of a severely disabled child needs respite care, so if I were PM, I wouldn't be giving him tax breaks any time soon.