Inevitably, whenever someone invents a new and innovative form of attempted aeronautical suicide, after the first few deaths and serious injuries legislation is applied.
Although there are now some deregulated sub-115kg microlights, their pilots are still required to hold valid pilot licences.
Why no central database of instructors and examiners? Because it would change so often that it would need full-time staff to maintain it. For which there is no funding. The preceived benefits simply do not justify the cost.