the basics about a Carnet

[PaulJ]

I am confused about some aspects of aquiring a carnet and if anyone can help out I would really appreciate it.
I understand that the 3 common ways of getting a carnet are:
- put up the money youself
- get some sort of insurance
- get a bank guarantee

Now like a lot of people I can't to put up the money myself, I don't know too much about the insurance but the bank guarantee seems the most obvious choice.
What I would like to know is...why would the bank guarantee such a potentially large some of money??? I spoke to someone at the HU UK meeting and they said it only cost them £75 to get a bank guarantee. But I still don't see what's in it for the bank? Ok so I've had my account at my particular bank for many years, maybe they just want to keep me as a customer??? But if I am heading off on a big trip which could take years, why would they care if I held an account with them or not, as I am clearly not going to be putting my salary cheque in my account anymore. What's to stop me driving off into the sunset and selling my bike wherever I like and leaving them to cough up the expenses??(not that I intend to!)
They are making a guarantee to the RAC that they will pay up if anything happens, but what is their guarantee that they will get their money back? Do you have to put your house up as guarantee?? I do not own a house so I can't do that!
If anyone can clarify this for me I would be very grateful as it is a big concern of mine.

------------------
My website