When I'm already logged into openid.stackexchange.com (aka SEOpenID) then I am able to log into stackexchange.com (aka SE) by simply clicking the button "Login with Stack Exchange". I am not asked for by SE for the SEOpenID email/password pair because it can detect that I'm already logged into SEOpenID. But if I'm not already logged into SEOpenID, then I'm being asked for the SEOpenID email/pass pair without redirecting to SEOpenID first and if I log in this way it means that now SE's got my credentials to log into SEOpenID itself, if it wanted to.
If I'm not already logged into SE, then meta.stackexchange.com (aka metaSE) will ask me for an email/password pair and seems to be no way to "log in with Stack Exchange". But if I log into SE first then refresh the browser tab with metaSE, then I'm logged into metaSE also! So no password was needed.
There are other sites which ask me for my SEOpenID email/password pair and not allow me to just click a button to be logged in with Stack Exchange, such as: stackoverflow.com askubuntu.com
This means that I have to type my email/password pair (those from the SEOpenID account!!) into those sites directly! Which means they now have the ability to log into my SEOpenID account and wherever else I'm using this account to log in.
A related question if you want to see what SEOpenID sees when I try to login to AskUbuntu (or even Stack Overflow) it's this SE owned IP 184.108.40.206 instead of my IP, as usual: Why does StackExchange itself login my OpenID account at StackExchange?
All these SE sites(apparently) are hosted on Fastly (Net Range 220.127.116.11 - 18.104.22.168) but openid.stackexchange.com is Stack Exchange, Inc. (Net Range 22.214.171.124 - 126.96.36.199)
So you see why I'd like to not give them(eg. Fastly) my SEOpenID password directly. Why can't these StackExchange sites(like askubuntu) just detect that I'm already logged into SEOpenID and just log me in that way? just like SE does.
The actual question is in the title. I don't want to give any site that's asking me to login, my SEOpenID password. But I still want to use only SEOpenID(not google/facebook) to log into them. How?