I don't pay for public transportation... (well, sometimes)
In order to use the buses where I live, you get a card and you have to purchase some kind of contract to use on the card. I used to buy the monthly pass because I use the bus on a daily basis (costs about 65$).
Recently a new app was released where you can provide your credit card details and pay via the app instead of the usual bus card. Each time you get on a bus you scan a barcode, choose the bus line and the destination and then you have to confirm. So what I've been doing is going through all the steps but without confirming. If I see that a ticket inspector is coming I quickly confirm and show him the receipt, but they don't come often so most times it's a free ride. Now on average I pay 5$ a month instead of 65.