In Colorado, you pay taxes on pizza boxes with leftovers, but not on to-go orders. A bill to repeal that just died.

http://www.denverpost.com/2017/01/26/why-you-pay-taxes-on-your-pizza-boxes-in-colorado/

Yeah, I'm sure the restaurants are separately accounting for all this stuff. Still, an interesting quirk in the exemption that more than a few states have.