This is true, there are some casinos out there which when one of their gamblers obtains a big win they try to find even the smallest detail they can to try to refuse paying the money they owe, and one way to do this is by asking way more than what is needed for a standard identity verification, with the hope the gambler fails to provide the needed documents and then they save themselves a lot of money while still protecting their reputation, as they can later claim it was the gambler the one that failed to pass all their tests and they were justified on their refusal to pay them.
In such casinos, players simply will not play. All players play at the casino only in the hope of a big win, but if they know that they will not be able to withdraw their winnings anyway, they will not play at this casino. They will go to another casino.
If only things were that simple, what you are saying makes sense but unfortunately this is not the way things work, and we have a very obvious example with the 1xbit casino, this casino is widely regarded on this forum as one in which no gambler should ever play if they want to someday get some of their money back, but people ignore our warnings or are not aware of the existence of this forum and they keep gambling there despite their negative reputation.
A gambler's gambling life goes awry when he doesn't get it despite his big winnings. There are many gamblers who don't listen to anything until their money is gone and when they lose it all they regret not listening to the advice. As warned in the forum about 1x bet I think after that if someone is cheated by betting then he is responsible for it. This casino has been completely banned by users on the forum.