I'm fairly cheap, and target good service at 10%, and do all in my power to stop tipping from creeping in to new areas of service. My sister is the opposite, and a 20% or 30% tip from her isn't unusual. When we go to one of her regular dining places you would not freaking believe the service we get, its like their long lost mother has walked in.
I would have told the kid, as I carefully loaded my own stuff, Gee this is new to me, lets go talk to your manager so I can figure out a proper tip.
Now how about tipping a tow truck driver?
When the wheel fell off my truck going through MO, the two tow trucks were there less than 30 minutes from the highway patrol calling them, and the town was 25 miles away, and it was the July 4th weekend.
One of them backed down the highway a mile to pickup my tire (I threw it off the road, but I wasn't about to carry it a mile uphill back to the truck.).
They hauled my pickup and car trailer to a shop, I unloaded my pickup (didn't want to leave anything valuable in it), then they gave me a ride to a motel, waited for me to get a room, helped carry my stuff up to the room, then gave me a ride to the bar.
Damn straight I tipped them.
If I get good service, I will tip well. Usually, by the time I walk in the bar, hang my coat on the chair, and get my darts out of my bag, the waitress is bringing me my beer. I usually don't even have time to sit down before it's there. Every time there's an inch of beer left in my glass, another one magically appears. I never have to ask, never have to worry about trying to get a drink in the middle of a dart game. It doesn't matter how many times I move around to different tables by different machines, my beer always appears where I'm at. She usually gets a 30-40% tip.
On the other hand, one place I went to a bit ago, the waitress showed up to take the order, and dropped off the bill. I had to go to the bar 3x to get my ice tea filled. Her "tip" was written on the back of the bill. "Next time, show up between taking the order, and dropping of this bill." No, they weren't busy, she chatted with five other servers for 20 minutes. Unfortunately for her, the manager walked by, and saw the "tip" before we had left, and talked to us. We ate their often, and she was not very impressed with that waitress. We ended up getting a $40 gift certificate since we had already paid for the meal, and the waitress was being hauled into the office when I left. I don't know if that's why, but that was the first and last time I saw her working there.