First, THERE IS NO CODE VIOLATION.
Depends on your location. I looked it up and here in the Netherlands this is against
NEN1010, our local safety guidelines for low-voltage installations. Yes they are guidelines and not strictly legally binding (this has gone to court several times actually, the main reason they're not binding is because they are not available for free which is absolutely ridiculous) but if you want to deviate from these guidelines you are required to show that your alternative is equally safe.
Apart from that we agree that interference is very unlikely to be a problem here. We also agree that this is not inherently unsafe by which I mean that the chance of this becoming actually unsafe is very small and if all materials are of good quality, undamaged and properly installed nothing will happen.
In practice though things can happen to make this situation unsafe. For instance if a sharp shard of building debris or whatever got into the conduit during construction. Then when pulling cable that debris could damage the insulation of both power lines and CAT6. Then, perhaps years later, the conduit gets flooded. I'll leave the rest to everbody's imagination.
Likely? Not
very much, but all disasters are caused by an unlikely sequence of events and with enough installs like this and given enough time it will happen. And in this case the result could be lethal. I see no reason to take this risk if it's easy to avoid.
I have been doing stuff all my life people tell me I can't do becuase they never try and just believe the crap they are told.
Just because it never went wrong for you (didn't cause an accident, I'm not talking about the interference bit) doesn't mean it can't go wrong. Some things occur so rarely that the chances of one person encountering it are small, but they still happen.