[JohnFen]

This is true, but two things mitigate it. The first is that if you're the one paying the bill, it's pretty easy to do so in a way that nobody you're with can tell how much, or if, you tip. The other thing is that the social consequences aren't that large.

In the end, it's voluntary behavior.

[vineyardmike]

To be transparent, if I saw someone not tip when they took the bill I’d say something. I’ve heard of people looking explicitly at tips when evaluating dates, because it’s perceived as a (vague) proxy for empathy. I’ve also seen workers complain to the customer over not tipping, so you can totally be “outed” by them too.

I’m against tipping like a lot of this thread, but it’s a standard practice in the US. Being the one non-tipper is not changing the system, you’re just hurting the service worker.