Why do people go to work sick & thereby spread their germs?

I realize the economy sucks, and that people need their jobs & the money they earn, and that in the particular situation I'm talking about, there really was no other option, as the guy running the store was the one who was sick, & had he not been there, the place couldn't've been open.

But as I sit here coughing my lungs out, dizzy from congestion, and generally feeling AWEFUL, none of that matters to me as much as wishing some idiot didn't pass his friggin' cold onto me (& apparently, at least one other person at the store) by showing up for work while he was contagious.

Selfish?

Yeah.
Sue me.
(But please wait until I feel better, first.)