And why should they ?? To quote Steve Eisman "incentives trump ethics every single time".

Here's a tax strategy that will greatly simplify all government efforts: any corporation with a market cap of 100bn+ is obliged to sign a privately negotiated deal with the gov to agree on a annual tax rate for the next X years. The minimum is set at 20% with no exceptions and can go up to 50% depending on the estimated negative social impact of the corporation. There are no write offs, no loopholes. Every year the tax bottomline is checked and enforced.

There is also a tax distribution enforced so that only a few can get the 20% one at any time. The goal of this to force a "bidding war" between them to get the lowest tax and the only way to do that is to reduce their negative impact to a bear minimum or stop existing altogether. Incentives.

Once that is set in place work on reducing the tax code complexity for everyone and everything below 100bn. Currently most if not all tax regimes try to shoehorn all entities under the sun under similar rules and then provide various kinds of tax write offs that create incentives to dodge tax and provides the biggest players with a massive advantage as they can hire specialists to focus on every single possible loophole to avoid paying anything.