Ive read the BA booking fees to be as 1% of the booking , in that a booking of 2 people costing £1000 would be £10 , if 4 people in a booking costing £1000 the fee would be £10 , if 1 person booked a flight in say First costing £4000 , the fee would be £40 , but the maximum is £20 so only £20 would be payable . If a booking of 2 people flying Club World at 2500 each , the total booking cost would be 5000 and a 1% fee would total £50 , but a max of £20 per person would mean a £40 fee payable . In fact the newer booking fees means that cheaper flights that now cost less than £500 per person would attract a lower booking fee than the previous flat fee of £5 per person , but for people booking more expensive flights like CW or first will pay more than the previous £5 per person flat fee .
https://www.britishairways.com/travel/gsanswer/public/en_gb?faqid=1160&gsLink=searchResults
I agree that companies in the the travel industry seem to think their customers should pay fees that are part of running their business is absurd , also the other types of fees like booking fees prevalent in the ticket industry ( concerts , theatres etc )
Just checked and it is 20 per person , so if a booking of 4 people buying £2000 tickets each a total of 8000 , it would cost £80 in fees ( £20 per person )
It does seem to penalise people buying expensive tickets , but I think most people think if you can afford a £2000 ticket you can afford a £20 fee !!! Also many companies do appear to levy a 2% fee for card use .