It's not as much about the fact that people don't want to do the work, it's about the quality of life said work allows. These cheap farm laborers need housing food schools medicine transportation goals a life.
What robots do is reduce all that ripple effect of societal load on all the other aspects of sustaining the labor force and their human needs.
Focusing on simply labor and it's price for the task at hand is stupidly myopic.
And reveals the greater impact autonomous robotic labor will really have.
Let's assume California's Central valley in 50 years time is vast swaths of robotic farms.
All other human infrastructure in these places die. Restaurants, stores, schools, housing, police fire etc fall back to early 1900s levels (or some smaller density level of the past)