There's a huge profit motive for, say, pharmaceutical companies to manufacture unsafe or deadly medicines, for food companies to manufacture unsafe food, etc.

There's a huge profit motive for, say, pharmaceutical companies to manufacture unsafe or deadly medicines, for food companies to manufacture unsafe food, etc. But laws, regulations, and agencies like the FDA keep them mostly in check. Yes, there have been some abuses and regulatory capture, but compare the state of US food and medicine before the creation of the FDA and after. The chances of corporations starting to murder authors to profit off public domain assets is unlikely, especially as everyone will be able to use those assets when they become public domain. It's exclusivity and artificial scarcity that earns these companies the most money (or corporations like Disney wouldn't have fought tooth and nail to extend copyright protections).