Different airports can levy different taxes/fees.

Anyways, one can simply not give business to a particular place when the tax is so high. I'm sure plenty of people are already avoiding the UK as a vacation spots or place to switch planes due to its very high cost. Airport tax is just a small portion of that expense.

Likewise, here in US, it makes sense to get out of many airports to rent cars where there's very high car rental fees/taxes from the airport lots.