Many European companies have been taking advantage of rules that allow citizens of European Union countries to work anywhere within the EU to hire subcontractors in countries with lower wages and fewer worker protections and put them to work in nations that would otherwise mandate better pay and working conditions. French president Emmanuel Macron has promised to push back against these practices as he tours central and eastern Europe, whose nations are often the source of such "posted" workers. The leaders of those nations, in turn, accuse Macron of protectionism, and of avoiding confrontation with the companies themselves.
See "France’s Macron Looks to Confront Eastern Europe Over Low-Cost Workers", Liz Alderman, New York Times, August 23, 2017