Gas stations can handle a broken pump or two because even urban locations typically have 4-6 pumps and busy highways have more. Moreover, filling takes 3-4 minutes at max.

Having one working charger at a highway-adjacent station could mean literally hours of waiting on a busy day, especially if you're waiting for a 50kW vehicle. Even if you get lucky most of the time, just the possibility of a multi-hour wait time would make most drives impractical.