A hydrogen powered ICE car will be just as maintenance intensive as current cars.
I wasn't thinking of burning H2 in an ICE - as you say, that'd be the worst of both worlds - but rather using it in a fuel cell to generate electricity. Like in the Honda Clarity Fuel Cell:
http://www.carmagazine.co.uk/car-reviews/honda/honda-clarity-fuel-cell-2017-review/So you get an electric car with a 400 mile range that can be refuelled in a few minutes at a conventional filling station (albeit one dispensing H2 rather than petrol).
... if you can do your supermarket shop while your car gets a full charge in the car park ...
Call me cynical, but I really don't think that's going to happen reliably. Every supermarket parking space in the country with charging points ? And there'll be one available when I really, REALLY, need it ? Wouldn't it be more sensible if, instead of putting in all those charging points, the supermarket replaced some of it's petrol pumps with H2 dispensers ?
Joe public votes with their wallet.
True, up to a point. For the many people (self included) who live in streets of terraced houses with no chance of charging at home, pure EVs are seriously bad news. I would welcome having the option of easier fuelling with hydrogen, and if I have to pay a bit more for that privilege then so be it ... because the alternative would be having no vehicle at all.
And as for the economics, yes, you're right, it's currently not very attractive for a variety of reasons. There needs to be lots of investment in the infrastructure and the vehicles to bring the costs down. So all I'm suggesting is that that seems a more sensible thing to invest in than putting hundreds of thousands (millions ??) of charging points all over the country.