The dots are not joined up. Councils are paying £27000 per "pupil" per year for the "pupil" to be at something that is evading being classified as a "school". If councils demanded that schools be registered before they paid them, that would be a step forward.
It seems that unregistered schools are there to provide supplementary education. They're not really there to provide a national curriculum education, as how can they in under 18 hours per week?