Are you merely being cynical, or do you have concrete information? Consider all the Jews named Levi, Levine, Levitz, etc.
Most Jews that I have met are best described as "non-practicing;" however, as you pointed out, they are generally aware of their heritage and ancestry.
Cohen and Cohn are also levitical names, as I understand it.
Admittedly, names like Levi, Levine and Levitz are typically Jewish but so are names like Goldberg, Lawrence and Einstein and I doubt that there was ever an Einstein tribe.
The Jewish friends that I know have no earthly idea to what tribe they belong and don't care. Perhaps they are not conservative Jews; I don't know.
No cynisism was intended on my part.