Both come down to money, nothing else.
If I offer enough money, I will get my cherry ES and that will get me better global scores in 3D01/05/06/AM3 than 100 ePowers. Plus, as long as I don't kill it, I can sell it and get most of my money back. No-one is gonna say that about a global GPU that's been e-Powered, or zombie'd in any way.
You are completely right, we can't track voltmods. a simple VR and two wires or.... Tin-level Zombie. I think a 4th league would help solve this, but HWB DO need more rules & guidelines for Pro Cup (IMO)