“The most disappointing example of this was when the Queensland government recently invested in [630 diesel buses]. Just when Australia is running out of diesel, these chaps are accelerating the problem. (https://www.smh.com.au/national/queensland/back-to-diesel-lnp-dumps-queensland-s-electric-bus-program-20260901-p60tg4.html).
Hydrogen has a very low round trip efficiency (less than 30% compared to batteries at 85%+). The energy efficiency is a physics hard limit, not just something we haven't solved yet.
The "cheap" hydrogen comes from natural gas (methane) through steam reforming, and actually contains less energy than the natural gas it came from.
The hydrogen from renewables currently costs about 50x as much as petrol for the same distance driven, and makes up less than 2% of all hydrogen used.
South Australia has tried both battery and hydrogen busses. It has just bought more battery busses, and has no plans for future hydrogen busses. Hydrogen for energy storage just doesn't make economic sense.