I find the last statement surprising. Yes, manual transmissions do require the occasional clutch replacement but also have less moving parts. So I would have assumed less maintenance.
Ah, but you're forgetting clutch plates, rollback arrestors, springs, and seals. The longevity is as expected dependent on driver and style as well
Labor has overtaken parts in terms of expense for service like this as well. I can easily bill the cost of a compact car for work done on a high end manual car (Porsche and high end mustangs for example)