You want to build a trillion dollar company? Fine. Corporate tax rate of 50%. You're a small business with less than $1M in revenue. Cool. Corporate tax rate of 0%.
Big companies will break up to take advantage of the tax code. Problem solved.
Instead, the bigger you are, the harder you can lobby for tax breaks. Currently, if you're a $1M company, that sucks. You pay 20%+. If you're Amazon, you pay $0.
A progressive corporate tax still makes some sense, and there's basically no excuse for their taxes being less simple than a citizen's. However active management is still required. Markets are fast and efficient but they are often dumb.
In what market are they a monopoly? Seriously. Amazon retail competes with walmart and target both of which offer online sales and AWS competes heavily with Azure and Google cloud. In what way is Amazon a monopoly?
The point is: you can give big companies whatever rate you want, but they're in the strongest position to circumvent it, and they will. The better choice is to lower taxes substantially and give the smaller companies a chance to accumulate capital faster, so they can compete.
But we could simplify the tax code... The bigger the surface area, the easier it is to find a vulnerability / loophole. And anymore, the tax code is basically being written by BigCos to protect their interests and provide breaks for themselves.
Enforcing a tax code that's 20-feet tall when printed out when companies are as complicated as they are -- it's a wonder anyone pays taxes. It would take years in court to figure out what a company honestly owes.
If it's simple -- you make x profit or y revenue -- then you pay z dollars -- for any public company, good luck grossly cheating that.
An essential point any plan like the GP's would be to make conduct like you describe illegal, and make sure those laws are adequately enforced and have enough teeth to be a deterrent.
Changing tax rates don't fix either of those.
Sales/Use/VAT tax for payments to wholly owned subsidiaries.
Large companies are perceived as being proportionally beneficial to the US economy. If you made the US a place that was meaningfully undesirable for corporations, they can leave. And even if these companies did not leave, you would strongly deter new companies. For instance imagine you were able to create your system such that it could not be simply avoided through various typical methods. So big companies really did risk losing up to 50% of their net. How long would it take before e.g. YCombinator started requiring new companies to incorporate in e.g. Hong Kong (or wherever) instead of the US? Perhaps even moving the entire operation abroad.
So even though I think this would be an absolutely incredible idea, I do not think it would work or be meaningfully considered in practice.
Here's an article about 2016: https://www.bloomberg.com/graphics/tax-inversion-tracker/
US citizens can't avoid worldwide taxation, but they certainly move states to avoid taxes.