My take.The typical worker today "at the lower end" is deunionised, precarious, in a very poor bargaining position. Corbyn's Labour was all over this and that was part of its appeal to young people. Don't know where you're getting your take from (well, media).
The food business of days gone by, was low paid work in pretty basic conditions, done by local people.
The business units my cousin bought were majority Eastern European workers. More men as I recall. It certainly looked tidier; I think safety was pretty good.
They kept costs down by charging for accommodation (in fact it was board really). That way you get people who are local to the factory, and you can make a bit on the accommodation side.
Customers in the UK don't really value food, and it's an ongoing challenge to keep costs down. If we invest in automation, we could further reduce the overheads, but that's capital intensive.