What chiefly happened -- in England, there are variations -- was that the lord fined serfs for not showing up for their duties. The serfs then got to do their own work (which they applied themselves to much more industriously), the lord got to hire day workers who knew the lord didn't have to rehire them if they didn't work hard enough for his taste, and the day workers got jobs.
This caused a lot of trouble around the Black Death because it was merely de facto commutation of servile duties to cash payments, and the lack of labor meant the lords tried to enforce the servile duties again.
What chiefly happened -- in England, there are variations -- was that the lord fined serfs for not showing up for their duties. The serfs then got to do their own work (which they applied themselves to much more industriously), the lord got to hire day workers who knew the lord didn't have to rehire them if they didn't work hard enough for his taste, and the day workers got jobs.
This caused a lot of trouble around the Black Death because it was merely de facto commutation of servile duties to cash payments, and the lack of labor meant the lords tried to enforce the servile duties again.
Even better than a promotion!