I had heard most of the “volunteer” inspections were just a lot of disgruntled drivers as well but that’s just second hand, I stay TF out of scales at all time
They don't want to do those per request inspections because they're meant to be random. And they shouldn't - just because brokers use them for a carrier verification. That's not what they're meant for.
As far as I have understood if you try to volunteer for an inspection they think that is you planned it and are completely ready ( I would hope you are), and are not at a random to catch you off guard with something wrong. That's as far as I seen it. When you want it you can't have it when you don't you get it. Go through the scale when an officer is there and look nervous and like your doing something wrong and he'll help you out
That only works for an annual inspection. I do my own annual inspections but, of course brokers/shippers dont care about those.