I have no idea where this lunatic idea of hypothecated taxes comes from - the idea that tax on something must be used only on that industry/group of people
the Govt have to find enough money to run the country - they normally try and do it in the easiest and cheapest way that also minimises the chances of evasion - hence PAYE, Fuel Duty, VAT, APD etc
it's like everything else - when only a few people do something it's not worth the effort to tax them - but when it gets to millions of holiday flights a year............
I'm sure they'd be happy to replace it with a fuel tax on jet fuel........