Canute .. nothing you mention would be directly to the benefit of the client .. only to the DJ and that sort of smacks of protectionism .. putting things in place to make it harder for someone to compete.OK I could not edit and add to my first reply to this post.
The standards can start by having all working DJs who say they operate as a business get a Business License from their City/County/State. Insurance should be mandatory. That will immediately eliminate a lot of those who have Bootleg hard Drives etc. In addition to this maybe there should be some kind of Basic course in Electronics/Electricity that one should have to take.
What DJs do in the execution of their duties can be of hazard and detriment to others. Placing speakers on poles over peoples heads. Electrical cords that can possibly be overloaded with Gear and Lighting equipment, safety practices at the Gig etc.
In the Entertainment business in Houston, strives have been made by other professionals in this direction. For instance, you have to have a license to be a Event/Wedding Planner if you are offering your services to the public. Same for a Caterer, you have to have a business license and a Current Health Certificate from the Department of Health.
These laws were created because there were so many people calling themselves Event Planners and Caterers who did not know what they were doing. This caused confusion among the unwittingly public. All it would take is enough DJs banding together and having enough signatures to petition for a Bill. The problem with that is, there are a lot of DJs who do not declare their DJ incomes so they won't care.
There should be basic business requirements, but those are state issues and in place where they saw fit. Insurance is a tricky one .. it's mainly there to protect you as the venue would normally have insurance to protect the client. "Basic Electronics"? .. c'mon .. I bet there are some phenomenal professional DJs that don't know or don't care how to hook up a system .. others do that for them .. that should not be a licensing requirement. Plugging into a breaker box should and is.
With some of the logic, we should license busboys, as they could inadvertently drop a knife onto someone's leg. Or the server could spill that hot bowl of soup. There is always recourse for all of those things in court .. don't need another set.