Close range sensors and secure transmissions. As long as the reader has to be within a couple of centimetres of the cards there's really nothing other players

Close range sensors and secure transmissions. As long as the reader has to be within a couple of centimetres of the cards there's really nothing other players at the table can do to get the data that isn't obvious. It's not like you can lean over the table and scan your opponent's cards with your phone without raising a few eyebrows. I'd guess the transmission of the card data from the table to the servers for the broadcast wasn't secure. Either because someone involved set it up that way on purpose to cheat, or because they had a 'password123' sort of password on it without thinking.