That's a fair point... It's another topic entirely, but if I had to guess it's because Federer has not much more to gain from this. He's not Djokovic, he's not Amazon... Federer is already ultra-popular and loved by pretty much everyone. So if he does something like it, we know he has little to gain extra in popularity from what he already has. I mean, I'm not saying if Djokovic or Amazon did it, they wouldn't do it purely out of good heart. But you never know. Also the fact that a lot of people like Federer's personality adds on to the fact as to why people would upvote this more and see this in a more positive light than for Amazon, which is a company with a lot of negativity behind it. It's not so surprising if you think about it.