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That's exactly what spam filters are. Since they are relying on heuristics and ML, they aren't completely accurate, unfortunately.

It is fair to criticize some of the obvious misses though - these algorithms and heuristics are clearly pretty bad.

Since a view years United Internet (mail.com, gmx.de, web.de) verifies some big players. So a email from Paypal, eBay or Postbank is visibly different from a standard email. (In the Web and App UI. Of course not if you use IMAP.) IIRC it has a individual icon and a green boarder.

(I don't know whether there is a standard behind it or if it is some kind of manual certificate pinning.)

The paid-for “Google Workspace” does mark emails that look suspicious. It also uses the well known Gmail interface.