You Be the Judge.....

Which method of paid parking would be easier to enforce?  In which instance could you quickly determine a violation without getting out of your vehicle, write the ticket only if needed, and move on to enforce the next space?  (click on each thumbnail to enlarge the photo)

POM card-only parking meter example with high-visibility enforcement signal
Pay and Display Ticket or Voucher
In-car meter

All photos were taken on the same rainy day, within minutes of each other. 

Additionally, driving around with a printout or cellphone trying to match up license plate numbers and space numbers is still not as fast and easy as driving down the street looking for the red flag on a parking meter.