I was tempted not to respond, but honestly this comment makes me slightly angry. As someone who is young, and works on software this comment does not seem very worldly to me. Have you seen the US government, Japan, and other places struggling to still switch away from antiquated technologies? Yes, they are partially incompetent, but also there is a certain level of justifiable trust in the system working in its current form.
> Grandpa also needs to do his banking online, his taxes, needs to manage his online identity, car registration, medical things.
No, they don't. They can use paper, phone, and fax still (at least in the USA). One of my grandparent's did this until very recently (when they sadly passed away) for most things. I was at one point told by the same grandparent that the "the familiar 'red yellow green blue'" you so describe they suspected was a virus and they don't understand how it appeared on their computer. Another grandparent struggled with the concept of folders (as in file explorers), and when they first received their a phone would shut it down and then was confused on why it wouldn't receive phone calls. These people were successful and educated (they had gone to college and used their degrees in their professional life). They just don't care about technology and when Apple makes a choice for them on the default browser they are happy.