I don't think I really understand the point you're trying to make. Absolutely, many migrants will see low paid jobs as a stepping stone to work.
My point was that in many communities, there are a lack of jobs. Traditionally, working class communities depended on industry for work, which paid relatively well. Since these jobs have ,diminished, since mines have closed and dock yards have dried up, the modern day equivalent are low paid call centres or supermarkets. These employ only a fraction of what industry once did.
Many companies get around paying the already insulting minimum wage by employing groups of migrant workers, to which a lower than minimum wage paying job might seem quite attractive when they pay more than your home country. Which in turn, leaves next to no jobs left for working class people in this country.
It is the fault of the companies who employ migrants at such a low cost.