Are the firms who claim to find an employer and get EB3-Unskilled Worker visa legal?

There is a Canadian-based immigration company that claim they have several opening positions at places like Burger King, Pizza Hut and some cleaning companies in US. In exchange of $50-60k they start acquiring Labor Certificate and file I-140 in EB3-Unskilled Worker visa category. They "claim" they do not pay anything to the employer thus not violating DOL's rule. Are these firms legal? If not, what rules they are violating?