Just to offer a counterpoint: my mother never used a computer and is non-technical, but she manages great with her iPad (she does chat, Facetime, and web browsing). She had a couple of hand down Android phones (IIRC, Moto E, Moto G, and later a Samsung Galaxy Note 4). The Android phones were very confusing to her and she had difficulty contacting anyone while on the go. She recently got an iPhone and she manages without trouble.
The problem is that there are a so many factors: prior experience (my mom used an iPad before), extremely small sample sizes, biases (if you are an iOS fan you like to believe that iDevices work better for your loved ones), etc.
There are only some aspects that we can objectively evaluate (iDevices get security updates for longer periods, iDevices typicaly get more frequent updates). When it comes to usability, you can only get meaningful information from large samples.
This is true of practically every comment on this site!
Remember when Windows 8 came out and people were asking for the start menu?
> Cognitively, he's the same, so it's not that.
When did he learn android? It's much harder for older people to learn new things especially when they're used to something else.
He's 3,000 miles away and doing support for him over the phone doesn't really work. So, I've sort of stopped trying. My step sister is smart, so I'm guessing he does it for her now. Of course, when I'm visiting, he unloads a bunch of questions on me and I try to explain the best I can. He suffers from what a lot of non-techs suffer from: they want the fish, not for you to tell them how to fish. I've tried to explain this to him and my SO, but I get that "why are you being an asshole?" look, even though I make the offer in the nicest possible way.
IMO a good ui concept doesn't need explanation. However many people never know because they never used one.
For example, he never used to send texts to my home phone number. Now half of them are, though I seem to have got him to switch to email.
He still can only send me pictures from his phone about 1 out of 4 times now.