> Even if there were no mortality or productivity benefits, you’d think cutting down on cold and flu would be sufficient motivation on its own.

You'd think that, but air-cleaning equipment that's not legally required is an avoidable expense. People getting sick, crippled, or even dying from things that aren't legally your fault doesn't appear on a company's balance sheets.

Given that, it's pretty obvious what a business that's out to save every dollar you can get away with will choose to do.