Service stations can be 300 km apart because this seems to be an acceptable distance with gas powered cars. If there is a demand for service stations every 150km, wouldn't you think they would be built?
The remote regions you describe, currently powered by diesel generators (where does that fuel come from?), isn't there an incentive to power them by solar and also charge electric cars that way?
And even if there are some remote spots on earth where electric cars are not useful, how large is the market share for cars for these regions? If Toyota continues to make land cruisers for those regions, what does it matter for eletrifying 99% of all other cars?
Generally with far apart service stations they can't be closer because everything between is desolate. These stations are already on the outskirts of civilization, there isn't support to have people drive an extra 150km to man a service station.
Depending on geography diesel comes from boats, tanker trucks or planes. Solar might start getting some niche use, but it's not reliable even with batteries at a reasonable scale. The main benefit to diesel generators is it's pretty easy to fix and maintain them with minimal equipment. The amount of diesel per person for a generator isn't that much, even smallish planes can carry about a week of diesel for about 10-20 people.
Service station distance is also a factor of gas supply chains. You need gas trucks to stop at stations every so often. They could be closer together, but that means more truck stops and that means more labor costs, etc.
EV charging stations just need an electric grid connection. Some maintenance/labor is still a good idea, but it isn't necessarily the same regularity and overhead costs of a trucking-based supply chain.
The remote regions you describe, currently powered by diesel generators (where does that fuel come from?), isn't there an incentive to power them by solar and also charge electric cars that way?
And even if there are some remote spots on earth where electric cars are not useful, how large is the market share for cars for these regions? If Toyota continues to make land cruisers for those regions, what does it matter for eletrifying 99% of all other cars?