No are they actively avoiding paying taxes or does poli just want 90%
Large corporations regularly do evade taxes (The spirit of the law, not the written word) by taking advantage of various legal loopholes yes. That's why some people have suggested "flat taxation" that has a fixed percentage, with no exceptions whatsoever and no legal loopholes.
Of course, that's completely ignoring why the US tax system got how it is in the first place.
Let's make an example of an actual real world scenario: Fuel taxing. Some big company complains (i.e lobbies) that they're being unfairly taxed on a certain product they're purchasing. Let's say that thing is fuel for their transport trucks. They have to buy all their fuel in their home state for whatever reason, and their home state has very high fuel tax. However, the neighbouring state, which they spend most of their time in trucking around, has a very low fuel tax. They argue that since they're mostly driving in a state with low fuel tax, they should be paying that lower fuel tax rate instead of the higher one. This argument is actually twofold; the state that they're driving in the most is missing out on all the fuel tax revenue that helps keep their roads in shape while the home state gets all of it, which is unfair to them.
This may sound like an unlikely scenario, but it's actually the exact opposite. I deal with this on a daily basis, it's very real, and it's called the International Fuel Tax Agreement (IFTA for short). It can be basically summed up as "Fuel tax on corporations should be divvied up based on how many miles they drive in different areas, not on where they buy their fuel." I regularly see companies getting multiple tens of thousands of dollars back per quarter because they buy all of their fuel in high-fuel-tax areas, and drive in mainly low-fuel-tax areas.
Now, this is just one of the multiple thousands of different rules on taxes that exist, and every time a big company or state complains (i.e. lobbies) about some form of unfair taxation against them, a new rule is added that will give people either less or more taxes. Repeat this over approximately 200 years and you got yourself the current US tax system.