The problem might be that citizens of Poland are the third most intelligent nation in EU... not much of a plumber or carpenter I guess....
http://www.amren.com/mtnews/archives/2006/03/germans_are_bra.php
notice that it’s only 1 IQ point between our nation and the top 2... :)
Even better! We’d have carpenters and plumbers that would actually know what they were doing.