Are easier to extract than other fuels, at least in terms of procedure but highly polluting and expensive for their customers.
There are other ways to produce power vehicles but are not enforced especially as long as there is oil from which can gather nice money. Fuel can be extracted from water by separating hydrogen from oxygen, which is very clean, but it find it very dangerous in traffic. And by a good reason it is. It can explode more easily and more devastating than the most filtered gas, which we don't want.
What else I do not understand it is something else. Why should we extract the all hydrogen from water and not only extract a small amount, as needed. For example if we had 10 gallons of water to extract fuel from it, we could only extract to 250 ml. The extracted hydrogen result would be about 166 ml, a small amount that would not cause a big explosion. In rest it emits oxygen, an oxygen molecule chemical compound of water. It may seem to those 166 ml not accounted, but are more efficient than gasoline. When the fuel finished continue to extract hydrogen from other 250 ml of water.
Why not go to another system if any?