Sun in my (dog's) eyes

In a recent Blog post I took a quick look at the song Yesterday’s Tomorrow, Today by Dream Quest. There is a lot more to be explored but what was interesting is I ended up quoting the song in a new way sense making the post. My wife and I were sitting outside and we saw a man walking his dog. What stood out to me was that the dog was wearing sunglasses while the owner was not. It was clear that the dog did not like the sunglasses and when the dog succeeded in getting them removed the owner quickly scolded the dog and put the sunglasses back into place, this happened twice. I was so confused by this. Why would he take such extreme steps to protect the dog’s eyes and not his own? I have not done any research on a condition that would cause this to be required for the dog, but to my wife and I it seemed like if it was super important then you would use a cone to prevent the dog from accessing the glasses. What matters is that my wife could see how confused I was about this and so sh...