This isn't the main reason running low and high voltage through the same conduit is not code compliant though.
The reason you don't mix low/high in the same raceway is because if exposed low/high voltage conductors come in contact with each other, the low voltage cable has a much higher chance of catching fire.
The reason you don't mix low/high in the same raceway is because if exposed low/high voltage conductors come in contact with each other, the low voltage cable has a much higher chance of catching fire.