[lqdc13]

Nowadays most routers I've seen come with a pre-shared key that's something like 20 chars long.

It's been the case with Comcast + Verizon for a while now. Not sure about AT&T.

Still might work 10% of the time though.

[paulgerhardt]

Some regional bias here.

Most of Asia (so most of the world) use digits only for their wifi password.

Lack of fluency with Latin characters was not a big concern in the original implementation. That should be fixed with WPA3

[lqdc13]

Why does that matter? 15 character digits-only password is impossible to crack really.

It's all about the length really.