I think part of the problem is USAG's ambiguous role in this. By maintaining the banned list and having a process through which people can be banned, the implication is that non-banned people are OK, and a phone call to USAG about a licensed coach that doesn't turn up any problems implies a clean bill of health. Furthermore, if USAG does NOT have a policy of accepting and acting upon reports sent to the national office, it should make that policy clear. There are multiple instances of individuals claiming that they sent letters to or called USAG with concerns about coaches; in some cases they were informed that USAG could not do anything, but in other cases, the letters/calls seem just to have been accepted without comment, which implies that something would be done.
For those unfamiliar with US employment -- in the US, there are two forms of ending employment. One is a voluntary separation, in which the employer and employee agree mutually to part ways, and the second is involuntary, when the employee is fired (and is therefore not eligible for unemployment insurance). In the different states, employees have stronger or weaker protections against involuntary separations, but in every state, it's possible to fire employees for cause, and the "cause" need not rise to the level of a criminal conviction. If USAG wants to play a productive role, it could certainly have a reporting system in which firings for cause of certified coaches were tracked. Some gym owners would still cut deals with bad guys just to get them to go away -- this happens in other contexts all the time where the employer says, "just leave and I will not make it impossible for you to draw unemployment " -- but it would allow the red flag to be raised sooner for more of these guys. A gym would go ahead and hire someone who's been fired for cause multiple times at its own peril, and possibly liability.
If there isn't already, USAG should develop and promulgate a strengthened set of best practices for member clubs in terms of how to conduct proper reference checks, how to spot predators who've made their way onto instructional staff, and simple policies to limit opportunities for abuse. A coach who takes a lot of photos of athletes not in a serious training context? Red flag. A coach who meets athletes outside of practice without supervision? Nope. A coach with a penchant for conducting closed-door private discussions with athletes? Not happening. If USAG doesn't develop the rules, they will be developed piecemeal by insurers as the suits roll in. It's probably better to have people who really know the industry developing the rules.
And I know it's not easy for gyms to talk about these issues with parents, but parents need to be part of the system, especially team parents who know the gym. It's the team parent, not the busy coach, the overwhelmed office manager, or the distracted owner, who's likely to spot someone in the gym who has no business being there, or notice that something weird is going on outside of practice. And the gym has to be an environment where owners are willing to hear negative feedback about their employees. Of course that will mean dealing with parents who don't know much about the sport complaining about Suzy not being moved up to Level 3, but if you have to listen to complaints about ten Suzies to get to the complaint about Coach Creepster, it's a worthwhile bargain to protect our kids, who are your kids too.