California tried to do it for everyone. Arnold famously had an all hydrogen fleet of personal Hummers back in 2004. The state had plans for a "hydrogen superhighway." I think they're up to about 8,000 vehicles on the road now nearly 20 years later, but that is nearly 100% of hydrogen vehicles in the entire US.

I think the actual state-owned fleets mostly switched to LNG by now. Who knows if it'll maybe be feasible soon for long haul trucking? Hydrogen cells started dropping enough in price to at least be feasible as a luxury good maybe a decade ago. This place seems optimistic? https://blog.ballard.com/fuel-cell-price-drop

Any experts in chemistry or industry have any idea how plausible those projections are? It's a vendor, so I take it with a grain of salt. A hydrogen city bus is still more than double the cost of a diesel bus, even before thinking about the need to refuel it.