In those cases, the onus needs to be on companies to provide safe working conditions. I don't know if they'd have to amend OSHA's authority for pandemics, but that meat processing plant in South Dakota is a prime example of a small area, with one 'factory' that caused a massive outbreak.
I'm not disagreeing with you, btw. I'm just trying to flesh this out a bit. We can't just go by 'common sense' or 'trust'. We don't necessarily need to 'enforce' either. However, there needs to be a level of control/enforcement at various points of entry, large shopping centers, businesses, etc. Government (local, state, fed) can't just tell people to please do something, they have to out there pushing the message.