....in which case you are better off with a pure electic vehicle, or, if you must, a range extended hybrid which can have its ICE turned off in an urban environment.
(also bear in mind that hydrogen production requires lots of heat and/or electricity)
I cant help but feel that those billions would have been better spent on improving other existing solutions.
The only advantage I can see is for energy companies (these things require lots of overall well to wheel energy) and as they have a more complicated parts that a typical BEV the makers of all the parts that will need replacing as they get corroded by the reactive hydrogen.
The only plus (as you correctly point out) is that like electric cars there are no ground level emmisions