For a while I have been working on the use of GPS in Meter Maid. Currently the outlook is that a small area of Amsterdam can be used as a pilot to discover and resolve issues.
Already the issue of GPS inaccuracy and zone borders has been addressed by overlapping zones and having the user pick the zone in case of an overlap.
If this really works then one click paid parking is getting a step closer. I hope to obtain sponsorship from one of the parking service providers to be able to include all Dutch cities. I've had two meetings with one of them already, so let's hope it works out.