Imagine if every company was responsible for making sure their catering services didn't poison their employees. Technically, every company could hire a food safety department to validate that every catered lunch wasn't toxic.
It would be a stupid waste of resources! Businesses should be able to just buy food that isn't toxic! Likewise, they should be able to simply put their money somewhere that isn't dangerous! So they can focus on the solving new problems that every isn't solving pointlessly in parallel.