Lots of reasons. So, here's some off the top of my head.
* Infrastructure - There's no hydrogen distribution system in place. Further, hydrogen is trickier to distribute/store. It's not like gas where you can just have a big empty metal drum that you fill and discharge. Consider, for example, that as gases expand they cool down and as they compress they heat up (Boyle's law). Now consider the danger of refilling, go too fast (with any sort of oxygen present) and you run the real risk of explosion. Without oxygen, you still have to deal with the heat generated. On the flip side, pulling hydrogen out of a tanker will cause the tanker and the stored hydrogen to freeze, forcing you to wait for a defrost if you go too fast.
* Hydrogen is not green. I know everyone THINKS that hydrogen production would primarily come from electrolysis, but that's not how commercial hydrogen is produced [1]. Instead, hydrogen primarily comes from fossil fuels (methane, natural gas).
* Related to the first point, charging a hydrogen vehicle would require all the same headaches the current EV connectors have gone through. You can't just specify a diameter and go from there. You must create a seal to prevent hydrogen from leaking from the pump. It's doable, but also dangerous if you get it wrong. Hydrogen is far more flammable than gas which is really super risky if someone is smoking while recharging.
* Electricity is already distributed. The fact that you are writing here on hacker news means you have a source of electricity that could potentially power your car. The EV charge station distribution is largely just a factor of setting up stations. Further, for relatively little money existing gas stations can easily be converted to support EVs. That's not so with Hydrogen. Another reason for the popularity of EVs is home charging is really fantastic. If you own a home and install a charger you'll almost never need any public fueling infrastructure. (also, with an EV charger refueling at home from 0 to 100 takes about 7 hours. Refueling for daily road trips generally takes more along the lines of 1 hour. Most cars are idle for more than an hour).
[1] https://www.eia.gov/energyexplained/hydrogen/production-of-h...
