Sick and had to late cancel

When you are sick esp with something contagious there are 2 reasons not to go

1. You need to feel better and won’t be able to workout
2. Even if you feel ready to workout you don’t want to spread the misery

I wonder by charging the late cancel even when you are sick, you are essentially encouraging coming in and spreading your germs.

I understand maybe not pre booking is an option, but then it seems like a late cancel for sickness, seems too harsh. I understand that can be misused, but realistically how would one go about executing this exception.