[Zarath]

Card counting schemes have almost nothing to do with the cards of others. I have no idea who you were watching but they sound like frauds. It's trivially easy to verify that counting systems work in theory. If you have a sufficiently good counting system, you will know exactly the cards remaining in the deck (Suppose I knew only 8s were left in the deck. I just never hit and let the dealer bust continually). Even the best human-capable counting systems only have an edge of 1-2%, meaning that you still need to get lucky or have a ton of time and a near infinite bankroll (minimize risk of ruin).

Having more players at the table hurts the efficiency of the count because more cards come out between when you place your bet, and when you receive both of your cards. This means that the correlation between the count when you place your bet, and the hand you receive, decreases.

House edge at good casinos is normally below 1%, and you're telling me an AI with perfect information couldn't beat a dealer whose moves are incapable of changing given new information?

Source: I've card counted for 6-7 years now

[zxcvbn4038]

If your playing with a six deck shoe and the casino is cutting at deck and a half, how much of an edge can you really get? Even if your the only player.

[Zarath]

Depends on your betting spread and table rules. But at a deck in a half you're probably looking at around 0.75% for a pretty standard ruleset [1]

The casino I usually play at cuts at under a deck and also has a side bet (Over Under 13) with even better odds than the blackjack game if you use a different count. It can also be gamed many other ways (they give $5 and $2.5 chips, but don't pay quarters, so if you bet $7.50 for your hand, they pay $11.50, essentially improving your odds even further).

[1] https://www.qfit.com/book/ModernBlackjackPage309.htm