[yuye]

Same in the Taipei Metro system. Stations often have facilities(like toilets, stores and lockers) within the paid area. However, getting in and out at the same station charges you the base cost: NT$20 (About US$0.66).

For example: You'd explain to the staff that you want to use the toilets, and they'll hand you a plastic NFC token coin, limited to enter and exit at the same station. You use that to enter the paid area, go to the toilet, then deposit the coin in a special slot to exit.

>Gate guards usually hand you a slip that explains the situation at the other gate or when leaving again.

That was done in the past, but it's quite nice that they just hand you a token now.

Alternatively, train stations in the Netherlands have done away with fees for entering and exiting the same station altogether. Toilets within stations often charge a €0,70 fee, though.