Seriously, why are they all there? Who/what are they supporting?
(Not outrage or sarcasm
, just don't get it
)
Umm...all the accredited photographers who use Canon.
There will be hundreds of accredited photographers from around the world converging on London for the Games.
They don't all own all of there own gear.
Canon and Nikon provide professional services like this at every major event - Every Grand Slam Tennis Open, Every F1 round, World Cup Soccer etc etc.
This is one of the reasons why I like the Melbourne GP so much...
I get to have a play with a whole heap of gear that I otherwise wouldn't have access to - 600mm, 800mm, 8-15mm fisheye etc etc etc.
The purpose is two fold -
1 - So you can keep working -
They have techs on site to do repairs etc to gear that may get damaged and so you can keep working, they loan you one of their bodies, lenses etc whilst the repair is being done.
2 - Marketing -
The other part is that you might just want to try a 1DX or the latest version of a particular lens.
You use it, you like it, you go out and buy it when you get back to your home base.