Why PEOPLE DONT use coffee mug ???

Einsteins's and Whole Food's give a nice discount for bringing your own cup. But, I just forget when I walk in, and it just seems so cheap to go back to the car for it. Anyway, that's my story and I am sticking to it ;-) I forget my recycle-able bags too.. (I usually take the furthest parking spot to get more walking in)

I think you're talking about bringing your own mug to a Starbucks or other coffee shop and having them fill the mug for you at a 10 cent discount. First those shops are a matter of convenience and it's inconvenient to have a mug with you and to take it in to wash after you use it. Second, I believe people are uncomfortable bringing their own mug in to a place that sells mugs, they probably have the thought that someone might think they're stilling hanging around in the back of their heads. Third why buy from Starbucks, if you're going to the trouble of bringing your own mug, bring your own coffee with the mug and bring your refills in a thermos.

Who will wash the mug?

I use my Gevalia coffee mugs, but sometimes I, like many other busy humans, don't have time to make coffee in the morning. I wind up having to go out and grab a cup, instead.

the same reason as to why people don't just make coffee at home...it is more convenient to just drive thru.

They do.

mugs can be heavy, and some dont fit in cupholders in cars, and they dont come with the convenient tops.

there are bio-degradable Paper cups used in some cafe's nowadays that are meant to be composted. Did you know that most companies who use paper donate to organizations who replant trees? Without trees they would sort of have no business...

I'm drinking tea out of a mug right now, although I do not recall receiving 10 cents for this. What else would someone drink out of, a plate? Unless you are talking about people buying coffee in a paper or plastic cup from shops, then I'm not sure that I understand your question. You should write it out more clearly.