In that situation I still tip, just less, since my "load" on the restaurant staff is much less, no one had to take me to a table, take my order, bring my order, and clean my table. The tip is for the kitchen and for boxing/bagging up my order in that case, essentially.

I hate that even that is required, though. I would gladly pay an extra 15-20% for the food itself if I didn't have to leave a tip & the staff was paid the "normal" minimum wage, or more.