I will admit that the installers are not among the best and brightest. AS a Head End Tech, I've had to work with them closely, because I was in charge of the Cable system telephony. That mean off the cuff troubleshooting, provisioning, etc. The installers, on the whole, that worked for my company, left a lot to be desired. We had a few that tried real hard or had some talent, etc.
Comcast does have some fairly minimally trained installers & techs and they won't hire seasoned techs. I know that from experience. It took me three months to get a return path cable plant problem resolved. If I had the proper equipment, it would have been resolved within an hour.