Well there are plenty of countries that aren't facing those conditions now, or in the recent past and still have shitty economies. It undersells how hard it is to build a strong economy and therefore undersells how hard Poland has worked.
being in the trade union helps, especially when for most part it was "cheap labour" for that union
You can provide cheap labor inside of a trading block and still be economically a mess, Mexico comes to mind and Turkey was sending workers to parts of Europe starting in the late 1940s. Poland did a lot more than just supply cheap labor, and it really undersells all of the work they've put in to develop their work force, education, economic policies, and so on.
But maybe that's because these countries did not have to struggle as hard as Poland did?
I don’t find that to be a very compelling argument.