Generally the corporations lobby, often with hard cash, for these laws that they've written.
Not in this case. There is pretty much universal agreement from business and economists that our current corporate tax laws are stupid and need to be reformed, especially the extraterritorial taxation that no other country does.
The problem is that many politician do not want to be seen as "giving in" to corporations, so they just keep the rates high, and then hand out plenty of loopholes to their donors.
Donald says he wants to fix this, but Donald says a lot of things.