You would be surprised how many people get this point all wrong, repeater ID'ing. Where the mistake is usually made is in reading the rules and missing the two usage cases, the first where only users all operating under the repeater's owner's license, closed, and the second where the repeater is "open" for use by any licensed GMRS user.
The first case is only users operating under the owner's license, and the only users allowed on it, closed, when they ID it is sufficient to ID the repeater. No self ID is required.
The second requires the repeater to self ID using some kind of automated control using the repeater owner's id, either by voice using English, or by Morse code, at the intervals specified by the rules.
It's not unusual to find general use, open, repeaters that fail to ID. Those are bad examples of what NOT to do, and are not operating per the FCC rules.