Non-pilot speaking
Many of them have a key-code on a pad to enter. On many flights, if you are in rows 1 or 2 and seats C or D, you can clearly see what the number is as the CC and FC enter the code. Whether the pads could have been better placed, or staff have not been told to shield their hands, who knows. Of course, if you are carrying something, then shielding the pad is more difficult. There are pads available where the buttons face up, rather than out.