krw wrote:

Keyword: yet. If labor costs rise above some point, one will
magically appear.

No, it won't appear by magic. It would appear if someone designs it.

There's another reason for the lack of mechanization as well, the
mechanized machinery requires more space between rows, which decreases
the yield per acre. I was visiting a winery up in Sonoma county, and the
owner was explaining how he and the next winery over had increased the
row spacing of the vines in order to allow for mechanize grape picking,
because labor was so hard to come by. He felt that yielding less grapes
per acre was worth the advantage of being able to pick by machine if
necessary.