What is your approach to tipping?

I’ve stopped tipping at places where I order from an iPad and I’m standing up, or sitting in my car.

Just today I ordered a coffee from Starbucks without anyone else in line, the guy looked annoyed I was there (prior to saying hello) no smile, no nothing, etc. I didn’t tip. Took them 30 seconds to make my coffee. The suggested tip on the screen STARTED at 20%. I’m supposed to add a 20% tip? That’s wild and I can’t reconcile with that.

Curious to know others’ thoughts.