Because the G80 works automatically, NO electronics, No input from the driver is needed ,
From personal experience; and I live in Snow Country in the mountains. I could pull up to a stop sign, snow or some partial ice on the road, and try to pull out, from that stop sigh on a slight uphill grade; and the G80 mechanical locker would allow me to pull out into traffic safely.
With electronic controlled or driver controlled, I would have had to hit a button or switch to engage the locking rear end. I imagine I did get it to pull out into traffic about 4 feet and one of the wheels hit an ice patch. Traffic coming and I am stuck half out in traffic. Talk about shixxing your pants!.
If I had the G80 mechanical locker; there would be no problem. If one tire hit an ice patch, pulling out from that stop sign, the G80 would automatically kick in and I would be moving.
I am NOT talking about rock climbing, where I would have time to shift the axle in; I am talking real world driving.