The "doors and locks" analogy is not perfectly applicable in this case.
In the cases of house front doors in the suburbs, the overwhelming expectation is both that the door is intended to be locked and that the public is not intended to freely come and go from the interior of the residences. This is a custom so well-established that it is essentially universal, and a house with the door open and unlocked is an obvious outlier.
In the case of fileservers on the public internet, the overwhelming expectation is that anyone may connect to them, and if anonymous logins are accepted, access the files on the server. Again, this is well-established custom.
Because the customary behaviour in the two situations are so different, the analogy is inapplicable.
In the cases of house front doors in the suburbs, the overwhelming expectation is both that the door is intended to be locked and that the public is not intended to freely come and go from the interior of the residences. This is a custom so well-established that it is essentially universal, and a house with the door open and unlocked is an obvious outlier.
In the case of fileservers on the public internet, the overwhelming expectation is that anyone may connect to them, and if anonymous logins are accepted, access the files on the server. Again, this is well-established custom.
Because the customary behaviour in the two situations are so different, the analogy is inapplicable.