Earlier quoted context omitted.
They were one man shops. 20 years ago, the going rate for installing a socket in an existing wired and ready to go junction box was $50. It's about a 5 minute job. I know it's about 5 minutes because I've done a lot of them myself. I'm sure prices have gone up a lot in the last couple decades.
The electrician is not charging to do a 5 minute job. They do not know that when they accept the job over the phone. They are charging for their time to drive to and from you, the possibility that the job is more involved than described, and the liability from doing the job. And the opportunity cost of not accepting a different job due to your job.
If I hired one to come out and do one socket, I'd be sure to get a $200 site visit charge added on.