I've also worked at places where the boss demanded a doctor's note to return to work. I just said "No, I'm not doing that." That's always been the end of it. I returned to work once I was well and continued we all continued on as if it never really was about health and safety in the first place. Lots of places have policies on the books that are either outright illegal or unenforceable, but they get people to tow the line out of fear. If a few of us call their bluff, it's better for them to quietly move on so that we don't escalate the situation and shine a light on that policy. If word got around that the policy was unenforceable, they wouldn't be able to bully the rest into compliance.

Moreover, not every "sick leave" is something that is contagious, migraines for example. I've even taken a sick day preemptively because I got to work and discovered that I'd have to work in close proximity to someone that was actually sick and contagious, but refused to stay home.

Also, if the company is requiring a professional evaluation in order to work, surely that is something that will be fully expensed to the company. I suppose that dynamic would be different under universal healthcare. But sending people that are recovering from a contagious disease that will resolve itself on its own would still be an incredible strain (and an unnecessary one) on the entire system.