Of course I tip. In many places, the minimum wage for waiters/waitresses is much lower than for any other workers because they're expected to make it up in tips. Which is absolutely ridiculous. But seriously, support them. They don't actually make a lot and those are pretty ****** jobs a lot of the time. My mom has always taught me that tip should be 20% of the bill before tax, subtracting or adding from there considering service quality. Minimum should be 10%, cause I mean who knows? Maybe they're having a terrible day and can't quite keep it in. Don't make their day worse. I usually go up to 30% because why not, right? If they're nice and I have money to spare, may as well do something nice like that.
It's not really about "owing" them anything. It's about keeping people's wages at a liveable standard and giving them a gift if you enjoy what they've done for you. It's not an obligation, but it's a decent thing to do.