The point of this thread is not about how you expose your images.
There is no standard. Some prefer darker/lighter... etc. we can talk about this for 100 years
I just wanted to theorizing some reasons why manufactures adjust the cameras the way they do.
By high end cameras, I meant D4 and 1Dx.
It seems like both NiCanon slightly under exposed the image a bit when the light metering at the middle.
Maybe I am too old school but I enjoy technical stuff
I think that the old "standard" exposure was to aim for 18% grey. That was just an arbitory choice, as I understand it.
If Canon and or Nikon now think 20% grey would be better it could be for all sorts of reasons. But all sorts of possible ideas are possible, and many people will be convinced they know why. To my mind I can't think of anything more likely than preserving highlights, and I like to do that. But many people like to ETTR, so I guess they don't worry so much about their highlights.
I was advised, by a professional that I respect, to over expose bright scenes and to under expose dark ones. This was to compensate for the "standard" exposure and to make the image more life like.