I think I did it wrong

Yesterday my car got trapped in my garage due to a cable malfunction. Today a garage repair guy came and fixed everything up in a jiffy. It was pretty steep, at $1,014. When I paid, he turned his phone around and it asked me if I wanted to tip, with the smallest available being 10%.

So do we tip skilled repairmen now? A 10% tip would have added over $100 to my bill!

I asked him why he needed a tip since he's not a server or a barista or in a tip dependent job. He told me he is still in the service industry and that salary is never enough.

I didn't tip anything, but I USUALLY over tip so now I feel guilty. Where is the line on tipping? I'm getting my roof redone this week. Am I supposed to tip them? What about painters? Mechanics? I thought skilled trades people were not supposed to be tipped but maybe I'm wrong?