I'm pretty sure its AP in the South. I think I recognise one of the staff.
While the costs are high I would point out its a not for profit organisation and the fees for therapy have to cover not just the therapists, but the premises, the supervisor, the cleaner, the admin person, the heating, travel expenses for staff, the telephone bill, toys, maintenance, staff training including regular whole day training days etc etc. You are not just paying for the therapist your fees have to cover the cost of the whole operation which is similar quality to what you would get in an American research university early intervention centre.
If you added up the similar costs in a school or hospital (%of building rent and upkeep and all staff including the caretaker,office staff etc per child) I imagine the costs would be very similar if not substantially more.
So when people say you can do it vastly cheaper you are not comparing like for like. If it is AP, I know the staff are not well paid and the whole operation is done on a shoestring. Staff would be vastly better paid if they became teachers or SLTs. Most staff start straight from university on minimum wage and are trained up intensively over months, similar to doing a teaching training or university course.
As anyone who has tried to run their own business will know £87 a hour isn't really that much when you have staff and premises to pay for.
For the State to run something similar it would have to set up a training college / intervention centre and staff it and would cost vastly more per child than this.
Yes you can get cheaper ABA in some parts of the country but those are usually people who have trained in an organisation like this and then set up on their own, so they have the benefit of the expensive training parents like these are paying for.