wizardofodds sees few AP's

Can anybody comment on this Q and A from wizardofodds.com:

Q. How many "successful" card counters, i.e. the ones who do it right, do you think are in a casino on any given night?

A. In would say in a large Strip type casino the number of counters who know what they are doing on a given night is in my best guess one half of a single person (or two casinos would have one person). The reason I think it is this low is in my many hundreds of hours at the blackjack tables I only spotted other counters twice.