Yes, very much so. There would have to be a degree of trust there. And of course registration issues if you're non-EU or you are EU and really want one of those cards to let you vote, get credit in PL, etc.
Renting without a contract repercussions in Poland
I am renting without a contract in Warsaw, Poland, I have a deal with the owner of the house and have been living here for 1 year
today a bailiff (komornik), came to the house and according to him, someone who is lives or lived here has a debt, e wrote down my name when he started interrogating me with my ID number (for fromalities) ,he told me the names of the debotrs and it wasn't the name of the owner or his family's name, the komornik asked me more questions about my presence and then it happened that he knew that I don't have an official contract with the owner of this house.
after I failed to contact the owner, he left him a paper asking him to present himself.
When the owner got back to me, he told me that he is aware of this issue and that he was trying to fix it before
The komornik came for the old debt of course, but will he also inform the authorities about me not having an official contract with the owner ?
And if he does, will I be penalized or will they penalize only the owner ?
You do not have a contract (official or otherwise) because the owner has not informed the tax authorities of the fact that he has income which needs to be taxed.
The only problem that I see for you is that one day you may come back and all your things are out in the corridor, and you will not have any recourse of action. The owner can do this anytime he wishes and change the locks. You will not be able to do anything and the police will not help you - as the owner can deny that you ever lived there. Now, if you want to carry on living there with that hanging over your head every day - then continue to do so.