why don't people cover their mouths when they cough?!

I have been sick since Sunday and now, while I'm feeling better in regards to fever, I have a horrible deep cough & sore throat & seem to be on the way to losing my voice.  I'm pretty sure I know how I got sick too.  We were in Michael's a few days beforehand, and as I rounded a corner with my cart, I nearly bumped into a woman coughing (deep raspy cough similar to what I have now) not covering her mouth.  Hello!  Please cover your mouth when you cough, especially out in public. We were less than a foot apart so I am sure I was definitely exposed to whatever she had.  Now Tessa seems to be sick too, but she is a trooper and still playing strong. (I am hoping too she may get the benefit of some of the antibodies in my breast milk.)  But that's just her personality.  She had a horrible vomiting & diarrhea illness around 18 months old (DH & I caught it afterwards and thought we would need an ambulance to keep us rehydrated, and it was all we could do to lie in bed and not moan).  But Tessa would throw up, play, throw up, play, throw up, and go right back to playing.  By the way, let me mention that was one of the huge perks of extended BF'ing (not the BF'ing while I was sick, of course) but the fact that Tessa refused to eat most everything and couldn't keep down water or juice either, but she kept down the BM.  Until she recovered completely, she mostly went back to just nursing for nutrition.  It was almost like nursing a newborn again.