An excellent question, yes many people want pictures with people in... generaly in terms of illustration unless your going into a specialised field i.e botanical, bird, insect etc. (lots of competition and not as much work available) you will find you will be asked to do work involving people as humanity is the most prevalent subject matter. How you handle people in your art, can be up to you, to fit with your own style and sensibilies; hopefully the client will have looked at your work before hand to know what this is. I'm not overly keen on people in my work so tend to keep their part in the image to a minimum if I can help it.

I didn' think of background artist  . But  yes that is true. But then I did take the post to mean subjects other than people and I wouldn't consider backgrounds as a subject in itself.