It's nice that Washington State and Seattle have laws and ordinances that protect basic rights of workers, but in most places that does not exist in the US. In many places it's $2.13 an hour which is supposed to be made up by tips to be at least $7.25 an hour.
In theory this is to be made up by the employer if tips dont reach $7.25 but in many right to work states making a fuss about that could land you unemployed. And even if that isn't an actual possibility, the fear of it keeps most quiet.
That's ignoring the outright insanity of saying $7.25 is remotely enough to get by anywhere in the US without forgoing food, safety, health, or the many things required to hold down a job (address, transportation, internet, phone).
I tip when I go out because I can and I don't know the employees situation. If I feel like I can't, I don't go out, get my hair cut, or get a taxi. I wish we didn't have this backwards racist system but I mean (look at us).
Obviously the iPad asks you to tip at silly times, like at the merch booth at a concert, this is a minor inconvenience, just hit no thanks and be ok
Edit: my succinct answer is, I tip when I feel like I am financially able and it's one of those situations I have always tipped in