You are more likely to have a gas fire in a garage. But either one can happen if you don't do the proper upkeep.
The Charging stations are paid for by a period of time. And they can be expensive. If you don't come for your car in a reasonable time that you paid for, it's gets towed. Not much difference than any parking garage than any other vehicle just a bit more expensive.
Shoot, on my bad day, I could do that just by doing something real stupid assembling the battery. Of course, any assembly should be done in a safe environment. I did have some real bad burns from screwing around and not paying attention. But I have never had a battery flame. Keep it within a certain temp, wire it correctly and pad it. The beginner is more likely to electrocute themselves than cause a vehicle fire. Mishandling 120 Volts at 10000 AH will kill.
I drive in the rain all the time. Everything is sealed including the wheels. Water did get into one pack and I had to replace the BMS system but that was from me ignoring a break in the container. No fire. In fact, no nothing. Luckily it happened at home where l had a spare battery pack.