The only reason we can think of is because they want to save money
Poles live in different ways than we do in the UK. We clearly define what purpose a room has - bedroom, living room etc. but it seems in Poland things arent so clearly set out.
My Polish business partner grew up in a family of 6 in a 40 sqm flat. Sleeping arrangements were shared and frontroom became bedroom at night. He now lives in a large house with his wife and child and where they sleep is flexible. Most of the rooms have sofas that become beds and they sleep where they feel comfortable. I see this quite often.
I also have friends whose flats dont actually have bathrooms. Ive got one friend whose shower is in the kitchen. Which takes some getting used to
