Help im confused on how this job is paying my fiance

Cassandra • 31 years old.. all about my family .. mommy of 3 girls..And loves spending time with family
My fiance got a mechanic job that apparently pays flat rate. Which means he only gets oaid for the work he does not hourly. So for example hes worked 8am to 1pm so far today and not gonna get paid a penny for that time because he hasnt had a car to do yet. This doesnt seem right.. anyone know about this