Conspiracy theory - natural gas

I read this article on seeking alpha this morning about some pretty startling and prohibitive licensing requirements for shops that want to do gas to natural gas fuel conversions for automobiles. Apparently due due to the conversion costs conversions only appeal to large fleets that drive very high miles.

I read enough of the comments to this article to convince me that there's at least a nugget of truth in here. I don't know that conversions vs. original manufacture is the way to go for proponents (see example from AT&T fleet here), but it does seem serious economic barriers have been put in place to keep consumers on gasoline even if you wanted to change.

Some other articles:
Who even know they exist? It's a pretty good summary article that discusses some of the vehicles on the road today - and indicates there are about 150,000 on the road currently in the U.S. and about 5 million worldwide. The article indicates many feel Natural Gas could have the largest impact if treated as a premium fuel for the most polluting and heavy duty vehicles if possible. Article also indicates there's not much consumer demand for natural gas vehicles.