This has been annoying me as well: WebAuthN even provides metadata that lets authenticators know which credentials they're willing to accept, so at least in that case (usually the flows where you have to enter a username), auto-selection should be possible.
With discoverable credentials (which Passkeys by definition are), i.e. the flows where you don't even enter a username and the website learns it from the selected passkey, I don't think there's a way around a key selection process, but the UI can definitely be improved to distinguish the two.
Maybe something like "website XYZ is trying to verify your account 'username' – is that ok?" vs. "website XYZ wants to authenticate you – which passkey do you want to present to them (if any)"?
With discoverable credentials (which Passkeys by definition are), i.e. the flows where you don't even enter a username and the website learns it from the selected passkey, I don't think there's a way around a key selection process, but the UI can definitely be improved to distinguish the two.
Maybe something like "website XYZ is trying to verify your account 'username' – is that ok?" vs. "website XYZ wants to authenticate you – which passkey do you want to present to them (if any)"?