Diesel engines why not more available in smaller vehicles ?

There use to be a number of diesel cars and small trucks. VW had the diesel Rabbit. Got great fuel mileage. Only took it about 2-3 miles to get up to highway speed. VW put the same diesel engine in a 'pickup' which wasn't much bigger than their Rabbit.
In the 1980s Buick had a diesel engine. The joke was the Buick diesel was the most theft proof car on the road. You could leave it parked anywhere, windows down, keys in the ignition. No one would steal it. It was a diesel.