But all the digital options aren't straight forward or understandable to the user, so.......
Signing things is easy. You just type your password in when prompted.
Verifying signatures is slightly more complicated, but considerably less so than verifying a paper signature. I mean, normally the way it works for
xkcd://1181 compliance testing of wet-ink signatures is that you look to see if there's a scribble that looks roughly equivalent to some reference scribble
[1]. If you need further verification, for wet ink you're hiring handwriting analysis expert witnesses or something. For an electronic signature, you're just checking some random string of ASCII matches some other random string of ASCII (which is probably automated by your email client anyway).
The only reason it's not 'easy' is that Microsoft/Google/Apple haven't made everyone do it
[2]. And the reason for that is because the law is still stuck in the fax era.
People not understanding cryptography is as irrelevant as people not understanding law. They still have to use it on a daily basis. (You did just now to read this post.)
[1] Authenticating reference scribbles is basically the same problem as authenticating PGP keys. Ultimately, you need people in a room who can say "yes, I was there, and I saw that happen".
[2] At a content level, at least. Try sending an email to a mainstream free webmail service user without valid DKIM and watch it get spam-bucketed.