And despite that expensive battery, it could only go about 100 miles on a charge. For a point of reference, my old Tesla has a nominal 85kWh battery, which I think is actually about 77kWh usable, so about 3x the capacity. And its range is somewhat weak compared to what's typical today.

It's a pretty decent approximation to say that the battery is the only problem for EVs. Everything else is either standard car stuff, or small/cheap/simple enough not to be a major problem. Nearly all of the progress in EVs that we've seen since the EV1 has been down to battery improvements. Take the EV1 and give it a modern battery and it'll be pretty decent. Take any modern EV and give it a 1999 battery and it'll be absolutely awful.