I drink coffee while driving on a regular basis. However, its in a Tervis Tumbler that has a snap on lid that has a small covered opening that I can slide open with my thumb to take a drink and slide closed again. I've tested it by filling it with water, snapping the lid on and turning it upside down. Not a drop comes out.
I'm more concerned about folks driving while talking on a cell phone. These are people that can't walk and chew gum at the same time. If its an emergency, pull off the road first. If it isn't an emergency, wait until you get to the next exit, take it, and then make the call. When I see somebody doing that in front of me, I slow down to widen the gap between us.