I have a 22-year-old and 14-year-old twins. They never paid a bit of attention to my tattoos until recently when I had coverup work done, changing things in a noticeable way.
My 22-year-old has done stick-and-pokes on herself, but very, very tiny ones, so far only on her big toe and ankle. I got her to do one on me, a bee on my knee, because I'm a medical person and I wanted to be sure she was using proper technique, especially if she decides to do them on others. I gave her disinfecting wipes, gloves, and drapes and stuff, and she did a great job on me, with good India ink. I'd rather have a machine than a stick-and-poke, though. I can zen out with the buzzing but the poking is really irritating and hard to get into a rhythm with, since it is slow.
One of the twins came to me with a design on her hand written with Sharpie, and she told me that she was figuring out what kind of tattoo she wants. I told her she wasn't getting anything until 18, and even then to consider things very, very carefully, especially placement as it relates to her job plans. She's thinking about law enforcement and a hand tattoo is not going to fly!
I don't object to the idea of 18-year-olds getting tattoos that they may someday regret, because tattoos are a reflection of your life's journey, to me, and they may require revamping or covering up at some point, but that doesn't have to be a big deal. As long as they're in a spot that can be hidden, when necessary, then there's no real issue. I didn't start getting tattooed until I was in my early 30s, but even when you're more mature you can make dumb tattoo decisions. I don't have any regrets about my own, but I have a friend in her 50s who got a completely awful one that she wishes she hadn't.