When you have a Google IG page (what is it actually reffered to as, My Google?) you don't get signed out of the website, and the cookies don't expire, so that you have to login again. Also, you get taken to mail without your password being asked. That's not safe now, is it?
With Yahoo! OTOH, you get signed out everytime you close the browser. So everytime you end up at their page, you have to sign in, again and again and again. Even if you just change service from, for example, Yahoo! Mail to My Yahoo!, you are asked to sign in again.

Either way, is it possible for Yahoo! to keep you signed in, or Google to sign you out after every time you close the browser?
With Yahoo! OTOH, you get signed out everytime you close the browser. So everytime you end up at their page, you have to sign in, again and again and again. Even if you just change service from, for example, Yahoo! Mail to My Yahoo!, you are asked to sign in again.
Either way, is it possible for Yahoo! to keep you signed in, or Google to sign you out after every time you close the browser?