It sounds like you want almost no government and people just pay for the services they want. Sadly this wouldn't work in practice and result in hundreds of thousands of people dying through starvation and lack of healthcare.
We had that system in our history and it wasn't a great place to live unless you were born into the 1%.
Tax allowances and MPs expenses are two different things.
Tax, in general, should only be paid once. You can't charge VAT on the materials to produce something you will then charge VAT on again.
However, I do think claiming VAT back on virtually anything you buy on your company credit card shouldn't be the case. I think there should be a requirement to prove the expense was wholly necessary to produce the goods/provide the services you sell before being able to claim it back.
For example, say a plumber buys a lap top and claims it as an 'expense' because he needs it to record his accounts, I'd say fair enough you can have that VAT free. If he then buys an iPad Air a week later and does the same I'd want to ask questions (to which he could claim the laptop broke and therein lies the problem, complexity of enforcement).