I don’t find it particularly surprising that some of the people freed by police after allegedly being kept as slaves at a travellers site say that they wanted to be there. For one, thing, that doesn’t tell you anything about what would have happened if they had tried to leave and been caught.
And there are a whole number of reasons why people picked up from soup kitchens and homeless shelters being kept as slaves might have found their situation preferable to the one they were in before. They had regular accommodation, no matter how squalid. They were wanted, if only for forced labour. As the local MP pointed out, they will have worked out there where everybody could see the condition they were in – and nobody apparently thought that worth remarking on. They had a reliable, if reliably inadequate, food. Perhaps some of them were made into pets, or even given a kind of kapo status. They had regular company. Above all, people can be treated much worse than they were allegedly treated and still behave like loyal, faithful dogs. Rebelling against your condition, as the people who escaped and complained to the police did, is entirely natural. So is accepting it. Neither acts determine what your actual condition was in the first place.
And it should hardly be so surprising that people accept the idea they have to work in order to receive the means of basic sustenance when this notion forms a large part of government policy on unemployment.