AK, CA, MN, MT, NV, OR, WA
So no principled justification to tip in those places, unless you like to tip for every service for some reason.
[1] https://www.dol.gov/agencies/whd/state/minimum-wage/tipped
While they may make minimum wage, in this day and age, minimum wage is well below what you might make otherwise at a non-tipping establishment. Tipping is still expected at restaurants in Washington state, and is still the main source of income for most servers (the minimum wage they earn is less than the tips they receive, and if it weren't for tips, they wouldn't bother doing the job for minimum wage).
I'm against the requirement to tip as a way of doing business, but will do it as long as it is expected. Ideally, we'd do things more like Europe or Japan.
However, these days, everyone barring McDonalds asks for a tip. I eat/take out less because of it, but I'll tip at least 10% even if there is no service involved.