certain provisions within Polish law, along with a number of legal and administrative obstacles
In other words, nothing to do with the EU.
I blame it on the bureaucratic vestiges of the old communist regime that politicians find convenient for dispensing political patronage jobs.
You blame it on that because you simply haven't got a clue how politics works.
It's pretty obvious that the strong brewery and distilling sectors have absolutely no interest in supporting a strong wine sector. They also have a great deal of influence, not least because Polish beers are starting to enjoy strong brand recognition in some foreign countries, but also because the vodka industry is very, very strong both domestically and internationally. Therefore, they have a vested interest (just like in the Good Ol' USA) to maintain their position.
Incidentally, Poland is considered to be far more capitalist than many other European countries.