Correct me if I'm wrong, but VOR can be jammed just as easily? It's effectively just ground based GPS.
There are actually devices, that can to a certain extent resist jamming by rejecting signal coming from some direction while amplifying signal from other. Typically they amplify signal from space and reject signal from ground where the jammers would be. So in a way GPS is more resilient against jamming if you can use this device. But AFAIK they are only used for military purposes.
Perhaps I'm misremembering things, but I'm pretty sure the SysVinit didn't run any "more restricted processes". It ran a bunch of bash scripts as root. Said bash scripts were often absolutely terrible.