With current technology we can communicate with within the limits of the speed of light.
Despite knowing close to nothing about this field, I'd hope that error-correction code would be somewhat simpler, resulting in less padding and more data going through. Think about the problems with dial-up telephones alone, lots of noisy lines and so you have to pad the data with enough error detection that it's still recoverable at the other end of the line.
It's been nearly two decades since I last studied this, but something about parity check matrices is screaming away in my head. Could be very wrong about that though.