The problem with that is that some of those rates are actually needed. The fire dpt. won't buy it's firetrucks from walking the neighbour's dog for a little change, for example. I think that the way to stop tax evasion is to simply make the tax money more useful. A good example from my own country: the police are being given tax money to basically be turned into paramilitary forces (which destroys the police's function as the bridge between the civilian and the government btw) while the firefighters & EMT's are still running with equipment from the 80's.
The same goes for piracy. I can't even tell you how many times I've bought something after I pirated it simply because it was really good! The Witcher 3 is a good example. So I don't think lowering the price will make a significant change (it will, but not be the winning deal) because according to some it will still be too high. And as others said, people will always find a way. We don't live in utopia, nothing is free. Taxes are a needed "evil", just as paying for content is. Because if you don't pay, who will? and if the creators aren't paid, what stops them from continuing to push out content from their ass when getting nothing in return?
Spend the tax money more useful/make better content, reduce piracy/tax evasion by a ton.