Then they need to be better at business. In american people are not unionizing to slack off, most of them just want better working conditions. If you're company cannot operate without exploiting people, maybe its time to change the business model.
But corporations don't have morals, so they'll continue to do as they do currently. If you want to change that, you should have legislation that makes them abide by whatever you think is immoral. Don't confuse your moral standard with that of amoral corporations who are incentivized to simply make as much money as possible.