Firstly, it's 20k OR 1 year, whichever comes first.
Secondly, a car that does 20k in a year probably does mostly motorway miles which are easy on the engine. On the motorway the miles get racked-up pretty quickly, but in term of actual working hours the engine does not too very much.
Thirdly, being a taxi driver you may do 20k in a year, but this schedule does NOT relate to vehicles used in 'extreme' conditions, and Vx gives as an example cars used as Police car,
TAXI, or towing. So no excuses, TD...
Thirdly, if you did still insist on adhering to the manufacturer's spec, then the engine will not go belly-up the next morning - the problem will appear further down the line, and since Omegas get scrapped with relatively low mileage due to the tensioner failure (80k/8y - remember?), most will not be around long enough to suffer the long-term consequences of manufacturer's-spec maintenance.
Fourthly, don't believe anything you read. I bet you actually think that Global Warming scare is real?