Those guys get paid by how many cases they can pack.

All harvest labor is like that. It's "piece work."

the owners put at edge of the field

Whether or not this has something to do with "American's not wanting these jobs" is apparently a mystery.

as that costs them time/money spent not packing lettuce.

It's also why children are effectively allowed to work in the fields as well. It's not just a job. It's a job your whole family can do!

rinse the shit off your hands in the ditch

A portable bucket toilet, with toilet paper, hand sanitizer, and a box of nitrile gloves would be all it takes. Like $50/day worth of expenses.

When private equity buys farms or even just the producers the farms supply they half ass everything and this is the "trickle down" effect.