Yes they do need to compress the gas and in most schemes it ends up having to be cooled to a liquid to get the energy density needed for long range travel.
I agree hydrogen is just a battery but it is in effect instantly rechargable.
BTW the thing nobody talks about are the oxides of nitrogen you get when you burn hydrogen in air. That is still simply a function of heat and nitrogen which is about 80% of air. You will still need pollution controls on your car.
