The key here is Toyota is biggest employer in Japan and when you add its suppliers it's even bigger. Toyota very much wants an Hydrogen future so that they can retain those jobs.
This article talks about the filler jobs and how the economy is stuck in the past.
https://news.yahoo.com/japan-future-stuck-past-220130554.htm...
Annoyingly I can't find the source that went into why they are pushing EVs.
Edit: To be clear that was the hypothesis of the source and they presented evidence that the government that backed it, like stressing job creation and the importance of the automotive industry, but there wasn't a smoking gun.