There are stops between those two places and “grape pickers” as you call them (though they do much more) also… do other things besides work. In fact, HSR will enable them to do those other things even more.

It will also allow people in those places to work other jobs besides “grape picking.”

Well, how about living in Merced and working in SF area? If a trip from Merced to SF would be less than 70mins, this would beat all rush-hour traffic along 101, and become viable living option.