The metro areas of such cities are often more restrictive, thinking they'll be able to eliminate the criminals coming out of the core city. They're also not really suburbs, unless you extend the term to cover places like Newark and the like.
Newark is indeed a suburb of New York City, it's also a city on it's own.
Look up what suburb means. Also look up with "metropolitan statistical area" means. Then tell me to look up what statistics exist in these new areas you just discovered.
As far as your random invocation of Luxemborg. It's great they're homicide rate is more than Germany. Their rate is also half of ours.
Stop moving the goalposts. Stop with the strawmen. Just stop. Walk away from the conversation because you keep wanting to change it to something you think you can win. The HILARIOUS thing is you're failing even more now.