This certificate industry has been such a racket. It's not even tacit that there are two completely separate issues that certificates and encryption solve. They get conflated and non technical users rightly get confused about which thing is trying to solve a problem they aren't sure why they have. The certificate authorities are quite in love that the self-signed certificate errors are turning redder, bolder, and big…
> A self signed certificate warning means "Warning! The admin on the site you're connecting to wants this conversation to be private but it hasn't been proven that he has 200 bucks for us to say he's cool" no. It means "even though this connection is encrypted, there is no way to tell you whether you are currently talking to that site or to NSA which is forwarding all of your traffic to the site you're on". Treating…
Maybe a security-conscious person thinks that, but the typical user does not knowingly choose http over https, and thus the danger of MitM and (unaccepted) snooping is at least as large for the former.
So it's somewhat debatable why we'd warn users that "hey, someone might be reading this and impersonating the site" for self-signed https but not http.