I do not think a black and white code compliant building exists
An argument is being manufactured here that doesn't exist. This was not what the OP asked. He/she asked a question on Article 517. I would also reiterate that it is logical to conclude that
IF the entire run of PVC conduit was 6-foot or less, that the OP would have specified that in the original post. Therefore my code-compliant answer did not speak to a run of PVC that is 6-foot or less.
Your comment exposes a fallacy of refuting a "caricatured" or "extreme version" of somebody's argument, rather than the actual argument they've made. Often this fallacy involves putting words into somebody's mouth by saying they've made arguments they haven't actually made. I could also interpret your reply comment as a Red Herring. This "Red Herring" tactic introduces irrelevant facts or arguments to distract from the question at hand. It is used quite a bit in the electrical forum. For example,
"No building is 100% code-compliant, therefore it is OK and acceptable to not install something according to Article NEC 517.13(A) - because since there is no totally code-compliant building, it all really doesn't matter in the big picture of things anyway."
Of course there are some grey codes.
So far, I haven't run across them in the electrical forum. Whether or not a "black and white" code compliant building exists or not has no relevance in this thread, or the code that is being discussed here. So let us try to stick to the topic at hand, shall we?
Topic:
NEC 517.13(A)
Q - is it permissible to use non-metallic (PVC conduit) below the slab and add an additional grounding wire verses EM conduit. Would this be allowed by code.
A - No.