Decades and decades ago, corporations paid most of the tax. People paid very little.
Then things shifted. Instead of taxing corporations, people were taxed. Said people, with less money in their pocket, required raises. And so, over time, tax shifted from corporate to personal, but with people in the end taking home approximately as much as they had before.
For example, you have $60k pretax, $50k take home. Tax rate goes up. You have less, demand a raise. You now make $65k pretax, yet have $50k take home.
Of course, the numbers are merely there for example.
Why all of this? Why a reduction on corporate taxes?
Well, because now corporations can exist anywhere on the planet. If you tax a corporation too high, it can move, and you have nothing to tax. It used to be that this thing called 'tariffs' and 'duties' were an equalizing factor.
If a car manufacturer moved off short to save corporate tax, why then you'd add import tariffs. The point being, the tariff was there to replace the lost corporate tax.
Of course, tariffs are 'bad', and the goal of international trade now, seems to be to lift the third world out of poverty. Which is a laudable goal, however, with no import taxes on many things, and with corporations able to move at whim?
You must keep corporate tax low, or you lose out to competing regions. This is doubly troublesome in a new economy, in which many goods are entirely virtual, and fly across borders on the Internet.
Thus, taxes remain at the personal level -- for people cannot easily move.
Right or wrong? Well, you have to get tax somewhere. And under the current model, it is hard to get it from corporations, squeeze too much, and they're gone. And this model is enabled by most 1st world governments world wide, which have decided that import tax, tariffs, are a bad thing.
The only alternative to more corporate tax, and less personal tax, is to re-enact import taxes, duty, that sort of thing. Else, how do you prevent corporations from moving?
Of course, it's not entirely as simple as all of this, but nothing at a 10000 foot view is. It's just an overview.