40.00GB = UK APD
7.90UB = UK Passenger Service Fee
1.30AY = US Passenger Civil Aviation Security Service Fee
14.80US = US Transportation tax
2.50XA = US Animal and plant health inspection services user fee
2.20XF = US PFC
3.50XY = US User immigration fee
2.70YC = US Custom user fee
You have to go through all those US services and they charge you for them.
74.90 in tax total in this example, but 47.90 of it is paying for UK charges levied. That's 64% of the total tax tab. It is not just the US that is saying to passengers, "bend over, relax, and smile."