Good card counters are always a team, you can't go far solo as it's pretty easy to tell when you're betting 20 dollars one hand, and 500 another.

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.