You can't get a professional tradesperson to show up for the most basic job for $250 in much of the country anymore. That's just the truck roll cost to come out and start the job.
They never really answered the question of how long the installer was there, or what the invoice stated. They could have easily spent 2+ hours getting to the location, understanding the job, pulling the cable, cleaning up, etc. It might have been $900 for one, $1500 for six - in which case nobody would bat an eye.
The price for one drop could very easily have been half of what you paid. Most of the work is taking the job, getting to the site, understanding what needs to be done at this particular location and getting started. Once you're there and working, adding a few more drops is comparatively little additional effort.