You usually have a few smaller players just playing fixed bets who call over some higher roller that will do the big betting when the count is high, and then just leave when the count gets low.
Rumor has it that the security cameras now have software that will tally the count automatically, and flag people that play when the count is up. Coupled with player identification (facial recognition/player rewards cards) and correlating player times, casinos are starting to automate this. All rumor, of course, but sounds plausible if you're willing to throw a few million at the problem.
Back in 2005 I was approached by one of the casino groups that was looking for a director of technology to manage the team that did "camera analytics". Seemed like a pretty neat job technically.
So I looked up the privacy policy of Holland Casinos and there is no mention of facial recognition, only mention of CCTV for security purposes (under which I wouldn't expect prevention of adverse losses to fall) and a seven day storage period of camera footage. They are not explicit but suggest they do not use camera data for profiling purposes.