I wrenched in a shop for a year too, and the owner had no clue about what brought in the money.
There was a big factory close by and they had a batch of like 50-60 beater bikes that they'd use to ride around their big yards. They'd throw them away, leave them out in the rain and weld some things back together when they broke. The owner was super happy to get this "contract" and just threw that our way hoping that we would get a lot of money from them.
There was only one 35 year-experience mechanic who could maybe get enough made in a day to make it profitable, but we would bring him the parts and do the billing so he'd only do the wrenching. The rate was 55$ per tune up, which included truing the wheels, adjusting derailleurs, shifters and brakes, checking derailleur hanger alignment, chain use, etc. and all bolts checked. They had a 15-20$ limit of replacement parts to add to each bike, so it was just an unsatisfying shitty job. Luckily I didn't have to do a single one and I honestly didn't mind filling out the service forms or building brand new bikes fresh out of the boxes!
There was also a lot of new old stock parts that nobody would ever buy : discoloured grips that spent their life in the window, basically all MTB tires were all models that nobody would us (Maxxis Ardents and Aspen, some Geax, Nevegals, etc.)... Looking back, I think it was mostly a road shop and that's a good thing as the 10K$ road bike people didn't mind paying for parts and labour.
All in all, I had dreamed my whole younger life that I'd love to work in a bike shop and wrench on bikes, but at 32 years old, stopping my masters half way and resorting to doing this for a living (at 12$/hour!), my dreams fell apart pretty quickly haha! Maybe I didn't end in the best shop in town, but still, it was one of the shittiest jobs I had done.