It's probably better that we don't have this feature - imagine the mess when the time server crashes and half the country ends up in a totally different time zone!
Any handset that has a built in GPS has access to an obscenely accurate real time clock source while the GPS receiver is on and tracking a few birds. Would be great Symbian app for someone to develop for the N95. Not quite as convenient as getting a time and date fix from the network, but a good second choice.
I think its called NITZ and as far as I am aware no network in Africa offers this!
The networks are probably concerned about the implications of being three seconds adrift... Just in case of a law suit from some idiot who missed his flight as he was late!