&Foo::foo can call itself. But you're not trying to call &Foo::foo. You're trying to call SUPER::foo, which will look for a &foo in any super class to Foo (when called from package Foo). I've often wanted this error message to be Can't locate object method "SUPER::foo" via package "Foo", just so you don't get all confused by this error message.

Hope I've helped,
ihb