In Houston, the most parking tickets are written for meter violations in front of the municipal court. Five times as many as in some areas. This is the court where people come to pay their parking fines.
So you go to court to pay your ticket and get another ticket while inside talking to the judge. The complaint is that when you get in there, you can’t just tell the judge to "hold it" while you go back out to feed the meter. The city is using technology to help solve the problem, with new P and D equipment that will accept credit cards and eventually cell phone payments that can be "topped up" from anywhere.
My guess is that the credit card feature will do more good that the cell phone. With the "card" you can buy more time than with the few quarters in your pocket. Chances are that folks simply don’t put in enough coins because they don’t have change, and if Houston is like most cities the court isn’t in an area with a bunch of 7-11s where you can go to get change for meters.
If the city is concerned about solving the problem (they are the most parking friendly city in the country), why not have a person with a change belt roving the area during the time court is open. They would collect more parking revenue, although fewer fines. However they would make a lot of friends and test whether or not my theory is correct (people aren’t born scofflaws, they just don’t have the change.)