I think for those best exchanges platform is the most expensive to list on for their coins. Because it makes a huge volume and real price that will release on your coins in exchange.
Yes, but most of the higher volume exchanges will surely take highest fee for listing the coin, there are many potential exchange taking higher fee for listing but at the same time companies should qualify their listing criteria otherwise they will not list even though they pay money to the exchanges.
The reason why they put high fees is because they dont want abusers or bad coins to be listed on their platform because that will only affect thier reputation .
aside from the high fee , there there is also strict rules that a coin dev must follow , like for example reaching a certain volume but volumes can be easily manipulated if the coin dev has alot of capital in which they can buy and sell using dummy acounts.