Andrew Dunn presents research which finds that many unemployed people prefer living on benefits to undertaking jobs which would increase their income, but which they consider unattractive.
There is of course the additional problem of declared underemployment - to remain within the embrace of benefits.
But governments like a quiet life, so they prefer to let these sleeping dogs lie. If they wanted to know more, they would only have to conduct a detailed pilot in a small area.
But it is more convenient for them not to know.