Industrial systems generally use some form of resistance grounding to limit the ground fault current that can flow into expensive equipment such as transformers, generators and large motors. The goal is limit damage to the steel cores in the event of a fault. Since industrial systems are relatively compact and consist mainly of cables, the fault current remains pretty constanst.
For utility systems, the concern is making sure that a phase conductor that falls on the ground, and other types of SLG faults will be detected and the line tripped off line. If the NGR is limiting the maximum fault current to 400A or less, the fault current down a transmission will quickly drop below levels that are reliably detectable. Utilities generally want more fault current, not less on long lines.
