I never tipped unless out at a restaurant and I received friendly service.. but somehow I felt guilty or something when I wouldn't tip the pizza delivery guy. Even though he was from the pizza place itself.. (before doordash and stuff)

Years later I started noticing outwardly hostile behaviour if I didn't tip. Bah.

I hate the look you get when you don't do it. Which is my issue. My own. I know lots probably feel the same. I'm definitely trying to overcome that nonsense.