nobody has to do the work, the work is voluntary. Eastern Europeans do the work because the wages are still higher than in Eastern Europe, so it makes financial sense for them to move to the UK.
In contrast to the exploitation narrative this is actually mutually beneficial. The food is produced at low cost which is good for consumers (in particular poor ones who would otherwise not have access to expensive vegetables), and the workers who earn higher wages than they otherwise would have.
This farm labour shortage would have happened in the UK no matter what - once Brexit had been finished if the UK followed through on the immigration promises they made to restrict inflows from EU. Don't know how representative it was but most of the "stealing our jobs" crowd was people who don't work from a sampling of interviews they showed on the BBC.
Maybe the "stealing out jobs crowd" are the ones competing for the lower wage jobs. I got the impression that Brexit voters were often towards the lower and of the earning spectrum. While I am for staying in the EU myself I can see why these people don't feel like they get much out of EU membership.
In contrast to the exploitation narrative this is actually mutually beneficial. The food is produced at low cost which is good for consumers (in particular poor ones who would otherwise not have access to expensive vegetables), and the workers who earn higher wages than they otherwise would have.