At Foxwoods over the New Years, at my table ($10 minimum) husband + wife were playing side by side - similar bets but not exactly the same. Both were experienced players with decent amounts at risk. Husband left table for bathroom or I think actually the ATM and told his wife how to play his positions. Dealer waited till guy left, then told wife he couldn't take instructions from her on another player's bets. Although I understand the rationale, it seemed nuts to antagonize these players.