Kinda strange that someone frequents a message board that is meant for observation and experience and demands "proof" for any statement of said observation.
In answer to your OP, although there are carts in many places, in NYC I have not seen a group going door to door in many years. That's just my personal observation. If you want proof of residency, well too bad.
I haven't stepped inside a KH in ten years, so I can't comment on attendance. I do see quite a few cars in the parking lot on Sunday. Although the local hall has 3 congo's and many of the cars may be there all day.
I do think that it's fair to say that the wits are on the decline and have been for awhile.