This problem isn't solved by the centralized App Store--even if it were good at blocking any app with functionality that would let it be used as a scam (which it is not)--as it is just as if not even easier to tell the person "your app is broken and you will need to use our website" and then give them the wrong URL.
Like, I don't understand what you are trying to accomplish here: you think your elderly parents are going to go through a number of steps to install software via a different process but won't go to a website? I bet going to a website would even be a prerequisite to sideloading, so why would the attacker bother adding even more steps?
You are thereby helping Apple do something bad for both society and large numbers of other people and you didn't even manage to get the one thing you wanted out of it :(.
That's was an example, but only an except. I think equally plausible is "my bank called and told me my app was broken and that I needed to redownload it. I tried logging into the new app with my bank username and password, but it didn't work. What's wrong with my phone?" Now, Apple doesn't have a perfect track record for catching and blocking these things. Their security controls are definitely better than not having them, though.
> The solution to this problem is EDUCATION
No, no, no. One of the things drilled into your head at security engineering and management conferences is not to ever trust the human factor. Education is a good thing to have in addition to all your other controls, but is a terrible first line of defense. People make terrible choices all the time. Maybe they're sick, or they've had a drink or three, or they're worried about something that happened at work, etc. etc. etc. Even smart people who've completed security training still make dumb mistakes.