I was a bit annoyed when they asked me to do it the 1st time I went there but I think they have to do it not only for insurance but to ensure you have read the joining details which are quite restrictive, there are no circuits, no visiting students and very strict joining procedures because of the fact it is in the middle of a City.
After you go for the 1st time you don't need to do the fax again. Although it is a pain in the ar$e for the 1st time, it is probably better in the long run that it is done that way and maybe other fields with NIMBY problems should do the same as there is nothing worse for them than a new visitor flying straight over the biggest complainers house!