People in the comments seem to think the barista likes supports tipping culture and resents customers who don’t tip, but that’s not the impression I get. He sympathizes with the awkwardness of the position and the tighter budgets people have, but nonetheless relies on tips for the meager amount they provide.
I hate tips as much as the next guy, but you should not protest by refusing to tip/undertipping in situations where there is a reasonable expectation of a tip. The only one who suffers in such a case is a low-wage worker. Rather, take your business somewhere without tips.