Two things need to be clarified in the following story:
- The large Canon bias is mostly because Reuters has tended to buy Canon product for thier staff. We are not looking at an un-biased sample in terms of brand. Plenty of photojournalists and other agencies have Nikon gear, it's just that Reuters is a Canon shop.
- One thing people aren't catching that I need to explain a little further: why ISO boost manually and not by Auto ISO? Simple: image quality. Every time you boost ISO by a stop you lose a stop of dynamic range, which is a real image quality difference. Every time you lower shutter speed by a stop you might get an image quality difference, but generally if you're above a certain bar, you get none. Thus, if you're optimizing for image quality, you never boost ISO unless your shutter speed would compromise image quality. Most Auto-ISO systems still don't get this quite right, and it seems clear that the Reuters photographers are exerting manual control over ISO, which means that they're directly managing image quality.