Being around freeride and DJ trails as much as I've been, you get pretty used to carting people out. This one was fortunately just a collarbone, and he took it like a champ.
My observations:
1) Always be less stressed out than the injured guy.
2) Even if the pain sucks, better to go to a hospital closer to home if possible (and sensible).
3) If you can get to hospital without an ambulance, that's probably going to be quicker in the long run.
4) If you ride with younger dudes, try to meet their parents at the trails; introductions at a hospital with "little johnny" all broken are pretty awkward.
Also remind me of old mate below. A little while on the green whistle, and he was having a great old time (even with a broken back). I hear he recently got airlifted out of another trail - unlucky bugger.
It was quite funny to us because once you told us of your stories and gave us reassurance that we shouldn't just freak out and call the ambulance, my mate was more than happy to drive back out to Westmead hospital.
He lives 2 mins walk away from there as well which was very useful.
We drove back out to his house and unpacked his bike for him etc.
He got his missus to help him change and put some betadine on his knee as well cause that was still bleeding.
Once we got that sorted he told us that when he got up to the hospital, the nurses nagged him about how long it took him to get to the hospital and how he went home first and got betadine on the knee etc.
Best part was that all they did was took some xrays, he waited around for ages being thankful that he actually went home first to change into something more comfortable and clean up.
Apparently it must have cracked back in when he was putting it into the sling and they were happy with just letting him go home with some pain killers and you were 100% right about just driving to the local hospital being the best course of action.