They are the fount of all knowledge and the source of some damn good yarns, but trying even to get the time of day out of them now is impossible. Long gone is the time when passengers would feel obliged to gasp with amazement as they listened to the cavalcade of stars whose backsides had graced the seats upon which they sat.
Now you're asking him who he's had in the back of his cab lately just to break the silence and the 'them and us feeling it inevitably creates.
I have been suffering silent journeys since Christmas and a recent trip confirmed my worst fears. My day had been long and hot and with a searing headache and the rail strike half-way through one of its 24-hour stints, I afforded myself the luxury of hailing a cab. No sooner had I stepped in than the protective glass screen was slammed shut.
I had been in mid sentence, but a reply came not from the driver but from the Rolling Stones crooning Honky Tonk Woman from a stereo riding shotgun in the front.
OK, I thought. If you don't want to talk, that's fine, and besides I love the Stones. I stretched my legs and fell into a newspaper. But as the sweat began to form and roll I realised just how hot it was and reached to open the window; to my horror it was locked. I knocked on the glass but by this time Mick and the boys were in full swing and my driver was lighting a fag and admiring the girl in the sports car alongside him.
All the macabre Luis Bunuel films I had seen flashed before my eyes. I would be ignored until I expired with heat stroke and then driven to a secret west London warehouse where the bodies of hundreds of talkative victims had been dumped, still lying in taxis with their newspapers strewn about.
But at journey's end, as I slid damply from the back seat and fumbled for the fare, my driver smiled and wished me a pleasant evening - hardly the sadistic cabbie I thought had been at the wheel.
So why the lack of communication? Why the silence? There's nothing I like more than a good bitch about life. Politicians, celebrities, the weather - they're all fair game. I always thought cabbies were great for that, always ready with an argument and a strong opinion.
What has happened to the likes of the cab driver who told TS Eliot that he'd confounded the great mind of Bertrand Russell, the philospher ('And I said to him, now Lord Russell, I said, what's life all about then? And you know, he couldn't tell me.')?
It's all come as quite a shock, so bring back the chat; bring back the boasting cabbies; bring back motorised conversation.