The IRS is pretty awesome and incredibly underfunded, yes.
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.