Public transport like urban buses and trams is paid in Poland except for a few towns. Passengers must have a card or single tickets which can be bought in ticket machines, either at stops or on board. Ticket inspectors raid vehicles at random and check tickets/cards.
The young man below didn`t have any. He tried to pay the fine with his debit card on the spot but he didn`t have enough money in the account. The inspectors demanded his id, he was reluctant to show it, so they threatened to call the police and he eventually gave in. They needed his id to send him a credit fine.
The cheapest ticket for 20 minutes costs 80 cents while the fine about 50$.