I recently watched Rain Man (1988). A memorable performance by Dustin Hoffman---the film either succeeds or fails based on whether his character plays. He deserved his Best Actor Oscar (though the protagonist of the film is Tom Cruise as Hoffman's brother--he's the one with the arc). I wonder how much came from Hoffman, how much from director Barry Levinson, how much from the screenplay?
Except that just having a guy sitting at the table next to you, generally letting you know what cards are left, isn't a very efficient way to count cards. Sure, you might get lucky in the short run, but the film treats it as if it's a sure thing.
1) Actually, it's not that hard to keep track of a six-deck shoe, since most systems will just have a running count divided by the number of decks left to get a true count--you don't have to know every card.
2) Cruise's betting patterns along (upping the bet when the odds are good) would probably be enough to give away he's counting. (If he's not upping the bet when the odds are good, then he has no particular advantage.)
3) Cruise and Hoffman talk at the table out loud about what sort of cards are left, so that pretty much gives away the game.
PS Hoffman's character has certain rituals he needs to perform to get by. One is watching Judge Wapner (RIP) at a certain time every day. Fine, except that show was syndicated. As they travel across the country, wouldn't it play at different times, if at all?