I think it's a difference between a more urban setting and a rural one. Some streets are too narrow for the big trucks with the "hands free" operation. There are also places with too many cars parked along the street to make the hands free method possible. New York City uses a system like Baltimore's. Years ago the Today Show had a segment where the host rode along with a garbage crew. It was really interesting. They were great folks, very funny. They came across some "disco rice" and the host asked what it was. They showed him a seething mass of maggots. (Mick Jagger knew what he was talking about when he sang, "Bite the Big Apple, don't mind the maggots." The sanitation workers in NYC are pretty well paid, and they earn every cent!