i think a lot of people dont understand who a lot of these unregistered provdiers are, and why other providers dont register with the NDIS, even Bill Shorten has been guilty of demonising unregistered providers, but I believe after meeting with people with a disability this week he has changed his tune a bit after they explained why they often choose (or need) to use unregistered providers.
The registration process is expensive and time consuming, mostly for little benefit to participants. Sole traders and small providers simply cannot afford to go through it, either financially or time wise. Others, such as allied health providers are registered through the own schemes. Many choose not to register with the NDIS for no gain. Other providers are places like Coles, KMart, sports stores and other shops when people buy a variety of legitimate items- forcing them to use registered providers will force them to pay more.