How are people using their headlamps so that they would need the ability to be run over by a car? I'm having a hard time imagining people putting their headlamps through such abuse, especially while they are attached to someone's head! Otherwise, they need to survive storage in pockets, bags, tight pockets of backpacks, maybe poor baggage handling if you put no care at all into packing, cold and heat, water, etc. I think the more likely failures are electrical - switches and stuff like that - and from what I've read in these forums, Surefires are not immune to those kinds of failures.
"Run over by a car" is probably a bad example.
I can think of a few personal examples why I'd want a near-indestructible headlamp:
1. Paragliding
Paragliding packs weigh about 50 lbs, and when we caravan to the top of a mountain, we pack a lot of people and equipment in one car or SUV (put 12 people and their 50 lb packs in one suburban once!). I like to keep a headlamp in my paragliding pack because sometimes I've landed out in a big field in the dark a few times, and it's good to have a headlamp to pack your paragliding wing and hike out.
Anyway when you pack a bunch of people in a vehicle and stack their paragliding packs, the ones on the bottom tend to get crushed. Right now I keep my headlamp in a crushproof Otterbox to ensure it won't be smashed, but the Otterbox is extra weight to fly with and lug around.
2. Rock climbing
It's good to have a headlamp around when rock climbing in case something happens and you need to hike out in the dark. Sometimes rock climbing packs get smashed because they're stacked, or if you throw them down into a gully before clambering down
3. Caving
I've caved a few times and liked it, and I'd like to go a few more times. Caving tends to be pretty rough on headlamps, because they get mounted on helmets, and depending on the cave you can be crawling on your hands and knees a lot (did one three hour cave trip where I was on hands and knees almost continuously). If the cave is that tight, you tend to bang your helmet/headlamp on the walls/ceiling a lot. For example, some cavers on the caving forums complain about the PT Apex because the hinge tends to break after being banged around in caves.
So personally, for me, a durable headlamp is very important.
Toshi