And that's the problem. You are correct: H2 is not a source of energy, just a form of energy storage that does burn cleanly. But it is very volatile, hence dangerous. There are a LOT of automobile accidents yearly; a more volatile, easily flammable fuel source guarantees many more deaths and disfigurements, not to mention all the problems with the new H2 distribution system you'd have to set up (i.e., thousands of gas stations now having H2 pumps).