I think it’s a case of looking at who is doing the purchasing.
Taking the current Enyaq offering:
SE L with suite and Plus pack is purchased by Motability to be leased to the customer. All including the additional pack is VAT Exempt.
Edition with Advance pack where the Edition is bought by Motability and the customer buys the Advance pack on top. VAT is only exempt if the customer qualifies by being a wheelchair user and the car is suitably adapted, otherwise VAT is payable on the additional pack despite the car as standard being exempt.
It’s not straight forward if you focus on the car but if you keep focus on who purchases, it becomes a little clearer.
I'm Autistic, if I say something you find offensive, please let me know, I can guarantee it was unintentional.
I'll try to give my honest opinion but am always open to learning.
Mark