Campy cable pull for rear derailleur

"Campagnolo has two standards of rear shift ratio. Old 1.4 and new 1.5. Also, not every shifter pulls the same amount of cable with each click. With 10 speed for example, there is more cable pull for “slower� speeds, than there is for the others. 2.5 mm pull five times (from smallest 1st to the 6th sprocket), 3 mm for 7th and 8th, then 3.5 mm for 9th and 10th. 2.83 mm average cable pull per click."

I am wondering if his is because the design of the Campy rear derailleur arc requires this to pull the chain the same distance between gears. Or are the gear centers at different actual distances for the same reason?