[ynniv]

"Hey grandma, run this and click Ok. Nevermind, just let me see it for a minute." Don't be a ridiculous strawman, everyone has friends or family they trust that are better aligned to their cause than multinational hardware vendors.

[pilif]

How do you make sure that grandma only does this if you tell her but not if the app she wants to watch that movie in or that email with your brother's address in the from field tell her to?

[bskap]

Everyone? They all have people that they trust, and at least one of those people is tech-savvy enough to evaluate root certificates?

[SAI_Peregrinus]

"Hey grandma, you won a new iPad! Just click here, then click ok in the box that pops up! Free iPad!"