Sounds like a feature to me. I'd love it if things worked that way.
People who are aware of how pervasive tracking is wouldn't mind much indeed. The average user would be _infuriated_ of having to login every time they open a tab.
Average users know how to use multiple tabs?
That's where LastPass, et. al. come to the rescue. Minimizes the annoyance of multiple logins, while increasing overall security if they didn't already use a password manager.
Minimizes, but does not remove.
I'll stick to Chrome when I want my browser to not lose my sessions constantly.
Even if credentials were stored in browser (ideally has a revocable token, not a password) and login was one-click?
There's only so long that all those angry, multi-tabbing, somehow-simultaneously-both-ignorant-and-power users will be infuriated at every single website before they forget it ever wasn't like that.
You can choose to “always open this site in this container” and have the cookie persist.
you can "reopen this tab in container: ..." by right clicking on a tab, so yes, but going "oh I needed google creds" is two clicks.