The thermal blanket (not always included!) is very useful when treating a wounded person - though last I used mine was to place it under the head of a Polish au-pair who ran across a busy dual carriageway at night and got hit by a minicab - it made her more comfortable until the ambulance arrived.
The burns blanket (again, not always included!) is also very useful, keeping damaged skin from infection etc.
Bandages can also help to some extent, though in most cases in order to be able to really help a seriously bleeding injured person - if bleeding from a limb - you will need a tourniquet, but these are not supplied with first aid kit because when used by an untrained person it can do more harm than good.
The latex gloves are also very useful, they prevent you from infecting the wound, and also protect you from contracting viral Hepatitis and HIV through minor cuts in your own skin.
Other bits - plasters etc - are OK if you have a child that manages to get a bruise, but will not make much different in a serious incident.
But - ultimately, first aid kits are inadequate for serious injuries!
Some years ago, a colleague borrowed a company van and gave it to his brother (with permission and insurance) who was a trained paramedic. The brother crashed into another vehicle and a young girl was very seriously hurt. The van was equipped with a rather comprehensive first aid kit. The brother later commented that when he tried to help the injured girl, there was absolutely nothing in the first aid kit that he could really use.
Also, recently a witness in the 7/7 enquiry commented that when he opened first aid kits provided by underground staff, he was dismayed as they had little useful items. He also mentioned the lack of a tourniquet. (and that it took 45 minuted before emergency services enetered the tunnel - apparently they were waiting at the higher levels for the all clear before going down)
In previous life, I was assigned field duties that required first aid training, and carried a simple tourniquet (hardened rubber belt) with me at all times. We were also trained at how to improvise a tourniquet of one was not available. I would say that if you could carry only one first aid item on you, it would have to be a tourniquet. But again, it's use requires training.
So going back to the first aid kit - it has some useful kit, as mentioned, but nothing that would make a huge difference in case of a serious injury. So I while I do recommend that everyone carry one in their boot - I do - I also think that those countries in Europe where such kit is mandatory, are going OTT. This should be down the best-practice and not down to a legal requirement, in my view anyway.
guess they didnt get too good a trade in price !!
