I don't think its a bug. its to keep you from getting late game vehicles at level one. think about it, if they started you with the DAN instead of the GMC this game would be boring. or oh I found a tank lets go back to Michigan. I have gotten the tayga at level one, wasn't easy nor was it really worth it until I could get better tires. But How many new players are going to do that? let alone know where it is without looking it up.
So yea, I'm not a fan of those missions either. They don't explain how to use the seismic scanner either. it just sits there and beeps until you figure it out. As much as I dislike those missions, I think it is a clever way to keep low level players in the first two maps.