A lot of these devices rely on security by obscurity and the fact that casinos have lots of cameras. Also, casinos expect any significant coordination between players and employees is caught eventually, because people are human and under film from multiple angles. Cheaters usually get greedy so they're easy to spot, because they don't know when to get out and some just can't help bragging anyway.

A lot of casinos are publicly traded so they're cheap as hell. The burden of dealing with cheap awful hardware/software is placed squarely on the employee's shoulders. "Corporate" thinks it understands security but will always buy stuff like this without consulting anyone that knows what they're doing.

This particular device isn't something you'd be able to access easily, you'd have to be an employee or risk being spotted screwing around with the machine. Or have a vendor badge ;)