i think its because trucks have a very low first gear... and when the truck is not loaded 2nd is almost as good as first. when it comes to assembled trucks and jeeps for that matter.. most of the time the transmission and the differentials are not matched properly. so the gearing is therefore really low.. so thats why there are quite a few out there who use 2nd gear to start off.. but i still belive if your truck is geared properly then 1st gear is always the best way to go...