It’s not about accents, it’s about whether you look/feel like a tourist. Even so, you can never really tell how people will go.

Source: I waited tables in NYC in a past life.

I have got family living in the US. All non-US.

Before they got state drivers licenses, they could only show their non-US ID/passport whenever they got carded for alcohol. A few times, the venue would just tack on a 20% service fee.

One time, they asked the table next to them if they also got a service fee: They didn't. They complained, got the service fee waived, then told them to forget about getting a tip at all.

You might guess a person might be a non-tipper, but giving shitty service or forcing a discriminatory service fee will make that a self-fulfilling prophecy.