Even if you think what you would say is obvious, please add. This is genuinely something I think makes sense regarding local bus routes given the longevity of light rail and how infrequently routes change, but I also suffer from confirmation bias, so I’m hoping for reasons this would be a terrible idea but obviously would prefer reasons it would be an even more amazing idea than I thought.
My guess is that hydrogen busses suffer the same challenges as hydrogen short-distance trucks. Due to an overall low energy efficiency (electrolysis -> compression -> decompression), it makes better sense for long-distance transport.