Very reasonable if there must be special conditions to be able to make withdrawals at no cost, because they require costs to carry out routine maintenance,
precisely sites that have no special conditions need to be suspected, how do they get profit if not many people are playing there while withdrawing is free?
you only need to compare which ones do not require a lot of requirements, so it is easier for you to make withdrawals.
I guess the logic works this way: before the withdrawal is done, there must be a deposit, and no gambler in his/her sane mind would make a deposit and then withdrawal right after. In between, there must be some games played. And in those games, the casinos are expecting to win, primarily because they have the edge.
So that's basically it. They don't mind the cheap withdrawal fee they give for free for as long as someone would open an account first and play. If the player loses, nothing is to be withdrawn. If the player wins, he/she will continue playing, well, until he/she loses.
That's basically attracting gamblers. After all, the competition among casinos is tight. They need a sweeter bait.