Yes, they actually do pay EI premiums.
It's not an easy issue to address, because the principle behind EI is that you're allowed to collect EI premiums if you're available for work in Canada, but of course the temporary foreign workers you mentioned leave the country and therefore are not eligible.
On the other hand, what we're asking employers to do is to provide consistent conditions for temporary foreign workers, i.e., if they work under the same conditions as Canadians, they will pay the same deductions as Canadians.
It's an issue we're aware of. I have to admit at this point that we don't have an answer for it, but we're looking at it. It's not an easy one to fix.