Yea, it's a problem with all these coin fiat operated machines. We recently had NEW fiat being printed, and coins replaced.... the older machines did not want to accept the NEW coins. {So you have NEW coins with the correct value, but the machine is still accepting old coins}
It is frustrating indeed. Bitcoin can solve that problem indeed and you will see more of that in the future. The only problem... it's still a machine and machines break down and components fail.
They should develop a parking APP for a mobile phone... you pre-load coins for parking, and when you approach these gates, you just scan and it opens the gate.... when you leave, you scan again, and your amount gets deducted, and the gate open again, for you to leave.
