Ive read the article, and I saw some interviews on a strawberry farm on TV. I went raspberry picking as a teenager in Scotland (where the best rasps are grown), great pocket money for a few weeks. We got picked up in the morning by bus, in our old clothes and with sandwiches and a drink in our bag, off we went for a days hard work. Often mums and children went, especially if dad wasn't well paid.
Most family units then consisted of dad working, and mum being at home or making 'pin money' when she could. So a few weeks at 'the berries' made a difference to the family coffers. Nowadays, it's not worth coming off benefits for seasonal work; it's physical work; it doesn't pay much above min wage. I also picked potatoes for a couple of weeks, now that was hard going.
Ten years or so ago, my niece, who worked for a veg grower, again in Scotland, was recruiting from Poland due to a lack of local interest.