The important thing is that there are legal hurdles about sales of domestic wines. Your post however incorrectly suggests that the EU is standing in the way of wine production (a surprise to the people of France, Italy, Hungary, Spain, the UK, Austria, Germany, etc).
Because Poland is a small wine producer and as a result it does not provide access to funds from national support programs, so Polish winemakers do not get the same support as France, Italy, Hungary, Spain, the UK, Austria, Germany.this is the reason most producers have plots of 0.5 to 2.5 ha.
the obstacles are Polish
A progressive change is in store for Polish winemakers: Polish winemaking law has reportedly been liberalized to allow a significant modification in practice for Polish winemakers. Polish Parliament approved an amendment to the Act on the Production and Bottling of Wine that assimilates Polish law to contemporary European regulations. The amendment repeals an existing law from 2004 and will come into effect fourteen days from the date of its publication. Accordingly, under the new law, Polish farmers will be able to sell their own fruit and grade wines and without registering as a business.