Previously Cape Town had parking meters into which you'd drop your coins. Traffic wardens would walk around and check if folk had put money into the meters, and if not (of if the meter had expired) attach a traffic fine to your vehicle.

A few years back this all changed - I suspect because, at night, people started stealing these little treasure chests on poles. Today we have officials wearing bright yellow and green bibs manning (almost) each street in the CBD. When you park, they ask you how long you expect to be staying and bill you on the spot for the amount of time that you estimate. On your return, if you'd overstayed your quoted time you pay up the difference, or get a refund if you were under time.

I normally quote the shortest time that I think I may need, take my receipt, and pay the difference upon my return. Most often I overpay and leave the difference to the official - who normally gladly accepts the difference with a smile. :)