SWBKCB
It's not a tax i.e. nothing to do with the government.
However :-
Although VAT is not chargable on travel such as air or rail fares being zero rated, this does not extend to the DTVA PFF which is standard rated & on such basis then DTV would be accountable for the vat on such revenue. This is backed up by DTV stating that the £6 receipt can be used as a vat receipt.
i.e. a net revenue to DTV of £5 & an output vat liability of £1.....?