Well mules a can go a lot of places rangers can't... And public land in a lot of states you can't have atv's or vehicles to drive through
I agree I'd rather ride a mule or horse than a ranger any day. I think it's more fun, and you can ride one right up in the fire and they're handy to drag one out. Those horses and mules don't get flat tires, run out of gas, get stuck, and don't make as much noise as a ranger does
