More than a few places that I go to regularly often "forget" things on my tab. I don't really ever tip less than 35% or 40% at those places. Every time I bring up the missing stuff, they just shrug it off. So I put it into their tip instead. I go to the places often enough and spend enough that I'm confident it's not hurting the business in a meaningful way. In fact, it's part of what makes me come back when I'm considering where to go on any given day.