Except when you get dispatched for that interesting sounding job "vehicle rollover down the bank" and get there to find either (a) no occupants in the car because they all walked to the nearest house and refuse transport or (b) the car absolutely trashed but the patient with not so much as a scratch, sitting on the side of the road, also refusing transport. As a cautionary story, though - we had a young bloke (30s) complaining of numbness in one side of his body, sudden onset. To cut a long story short, he was in a side impact RTA the day before. The car had hit the passenger side, and the passenger's head had hit him in the head/neck. He refused transport. Internal injuries had caused a clot which had eventually jogged loose and made its way to the brain the following day. He ended up crashing at the hospital and last I heard he was in ICU. It always pays to get checked out (although in reality it may not have helped this particular guy).