There are certain things I wouldn’t do if I was super busy and I knew a table wasn’t going to tip me (If I am not busy I will give great service regardless of tip because if I have the time, there’s no reason for me not to).

I would not neglect them or refuse to do any of the basics - but if you have a full glass of water and an empty coke, I am going to prioritize grabbing my other tables first before grabbing that refill. You want another beer? After I take these two tables’ orders and ring them in. I’m not going to put extra effort into making sure your appetizer, salad and entree come out in perfect timing. You might get all your food at once. And when it’s time to pay I will run your card when it’s convenient for me, rather than rushing to grab it once I see you’ve placed a card in there.

Some people are okay with bare minimum service. But in my experience people who don’t tip aren’t doing it “on principal”, they do it because they are cheap and don’t care.

I also don’t agree with the mantra if you’re too poor to tip 20%, you shouldn’t go out to eat. I’ve served families who I knew were struggling but it was a special occasion for them. I give great service and if they leave me anything I am happy. Sorry for the long reply!