That's a good question.
We know that they some of the pharmaceutical companies, like Merck, have been charged with continuing to market and sell other drugs that they KNEW were killing people. They have paid HUGE fines. And they have been sued for those other drugs.
However, they are immune from law suits for vaccines. That would just make them even LESS careful than they usually are. They have already shown their true colors with drugs that they can be sued for, so how much worse would they be for drugs that the government protects them from being sued for, no matter now careless they may be manufacturing them?