There were a lot of tax write offs through incentives which was a good thing because it actually encouraged rich people and businesses to be proactively productive towards the public good.

So done right, they paid nowhere near the 80%. Of course there was abuse and loopholes.

And off topic and contrary to popular thought, Jimmy Carter was the one who started deregulation in this area. He was trying to get the economy moving again and was taking a "reasonable" approach. Reagan took Carter's idea and went on a heist with it to enrich buddies and doners