Child protective services seem like exactly the kind of job that you cannot do if you care too much about the kids you see. For very similar reasons to the doctor example. The entire job is visiting children in terrible situations and deciding whether forcibly taking them away from their homes and families would better for them on-the-balance. If you get it wrong you might make things far worse for the very kids you want to help, and even the ideal outcome may still suck for everyone involved. Personally, I could never do it. Certainly not while keeping my sanity