Speculatively speaking:
Not every person with measles is showing symptoms at all times. None of us want it.
What could we do to stop ourselves from accidentally contracting this crap, aside from staying home all the time (lol), avoiding human contact, sanitizing and washing our hands, wearing a mask, and stuff like that?
You could get a disease from someone preparing your food, especially if they are for some reason pissed at you and spits in your food or w/e, handing your ID to someone at the liquor store or a cop on a traffic stop, getting coughed on at the grocery store, etc etc etc.
This shit is getting out of hand and we all have families to protect.