You're supposed to tip for EXCEPTIONAL service, for going above and beyond the expectations for your job. If you just doing regular ass shit, you don't deserve a tip. If I'm a repeat customer, and you remember my favorite drink or a specific appetizer I always order and got it ready as soon as I sit down, that's deserving of a tip. If the wine you recommended paired really well with dinner, you deserve a tip. If the desert you recommeneded really was the best I've ever had, you deserve a tip. But just doing your job??? Nah b.
Back when I worked in car audio, I used to make sure my installers got tipped when they did shit outside the norm or had a particularly hard car to work on. If you had work done at another shop and my installer cleaned it up, you needed to tip him. If he made the shit look nice and neat under the hood, you had to tip him. Anything special, you need to throw them dudes some lunch money. Back then, an 80's Buick Century or Cutlass Ciera was an automatic tip 'cause niggas always got their hands sliced up gettin the old radios out.
Just doing regular ass shit didn't warrant a tip 'cause that's the job they were getting paid for anyways.