I've had someone rack their slide with their pistol side ways facing me a couple times. They don't even know what they'd did wrong a lot. I wouldn't want to be a RSO that's for sure. Even marines who are grilled in and out about their weapons 24/7 have tons of negligent discharges. I think is just human nature for a percentage of us to be bone heads.
In a sense, this is why it's necessary to have ROs. Keep in mind, we must always be cognizant that this range can/will be shutdown should a serious incident occur.
A few months ago, a pistol shooter pointed a gun at a RO and pulled the trigger. The gun went off, but did not fire, because the RO wedged the web of his hand into the hammer and disarmed the shooter with the assistance of another RO.
The gun was cleared and a round ejected. Had that RO, or any other range user, been killed, we have been informed that the range would shutdown permanently.
Range users need to keep in mind that ROs deal with EVERYONE throughout the day. The RO may or may not know you, but most likely, a rules violator is someone who is unfamiliar, and should be approached with caution and expeditiously, especially if muzzle sweeping. Unfortunately, that does translate into yelling.
Imagine having a loaded gun pointed at you four-six times a day, sometimes more. That's the life of an RO. Some of the methods differ from RO-to-RO, but as with everything, you build rapport and follow the rules, your range day is more enjoyable.
However, the most dangerous words are "I know," and the most dangerous item at the range is an "unloaded firearm." ROs are human and have good days and bad days. Keep in mind that they are ALL gun guys, and are working to ensure safety and that the rules are enforced as to ensure the range usage for all into perpetuity. We are all one serious injury away from losing the range entirely.