Food delivery services usually need to know the phone number of their customers, to guarantee that the deliveries will be smooth.

So, a food delivery app would probably prefer authenticating users by phone number rather than by email address.

Phone auth on its own isn’t particularly secure, though, so it would be nice to allow users to optionally add email authentication as a second factor.

As of right now, phone auth doesn’t support MFA, though, which means that a food delivery app might want to force users to use email and phone 2FA right away, which might seem intrusive to users, even if you implement anonymous auth and explain why you’re asking for both email and phone.