>>4489845B&W dev is done by hand, and C41 film is done by machine automation.
I've seen a moderate rise of C41 B&W film being sold locally this past year or so. Local shop has sold a lot more XP2 Super than even HP5 according to the owner. The film is like an extra two bucks per roll but costs 2/3rd the dev cost at the same store so it's actually more economical.
Besides, think of how much time it takes you to dev a single roll at home. Even if you've done it a hundred times and have all the chems ready to go, it still takes you a good 20-30 minutes to go through everything all the way to drying. I'm not surprised shops are charging $20 USD a roll to have an intern spend a solid half an hour on a single job.