For many years it appeared the wine industry was on its way to total mechanization of the harvest. Then the INS stopped it's raids (which used to drive the wineries and grape growers nuts). Now picking machines are few and far between. The excuse for their non use is that they BRUISE the grapes and the invading foreign national pickers are so much kinder to the vines!!
Mechanization works in other countries (ie Australia). They don't seem to need a massive influx of illegals. This whole thing is about voting blocks.