Probably because farm labor is skilled labor and seasonal. It sucks to live out of a vehicle traveling with the crop harvest. If you want them to work just within the area you need to make the month or two of work worth more than just a month or two of wages, because they will soon have zero work and will fuck over holding other non-seasonal jobs while every other seasonal industry also competes for that labor. Agriculture is also exempt from overtime pay. On top of all that, you can't just throw some rando in a field and expect them to get anywhere near the output of an experienced picker, especially with 12 hour days and a physical workload far higher than most people have ever experienced.

Their meager wage increase is not worth uprooting your entire life just for 2 months or less of work unless you are sending that money back to a country where a dollar goes much farther. They need far more than just add 2 bucks to an already way underpaid job to not only attract workers now but keep them around and available for following years.

>if the labor pipeline dries up (which is a very real thing as immigration has decreased in North America/the US) then no one will be doing that job.

>i suspect the amount of money that farms would need to pay workers to fix these shortages would drive all producers into bankruptcy

I definitely think it's the latter rather than the former. Producers being driven to bankruptcy is an issue, but that seems like it's something that's going to happen regardless if we made "non-STEM work to be a viable option". At the end of the day, if it's a shitty job, then you'll have to pay more to get people to show up.