I think one should always use common sense when photographing people, be it adults or children. I will never photograph a person who is in a derelict situation, or someone who is in a compromising pose like revealing something by accident or something like that. With children I think one needs to be extra careful. When I photographed the children on the square with the fountain, there was one up close shot of one of the girls that I thought was revealing. I deleted it, because it wasn't any good anyway, but even if it would have been a good pic, I would never put it online.
But, other than that, I photograph people freely and cheerfully. Not often as it's not really my thing, but if I do, I do. I never ever do it with a telephoto lens though, or hiding behind a tree or fence or whatever. I use a wide angle to standard lens, like the 28mm on my old 5D Classic. Or even use my Samyang 14mm some times. I am therefore close to the people I photograph and part of the scene. I am a woman, not young any more, with a nice, friendly face, I smile a lot, look people in the eye, often talk to them and only had one really negative experience with an elderly woman; she was following people around, urging them in a loud voice to give their hearts to Jesus or something like that. She very much objected to me taking her picture. I thought it was rather funny that she said she had a problem with me taking her picture without her permission while she herself was trying to shove her religious beliefs down the throats of other people without their permission. She however couldn't see the humour in it... 