Most of these casino just do all these because of the government rules that are tied to them operating their business. These casino are now implementing all these to avoid be sanctioned of money laundering law because most of the users deem their site to be a perfect spot for huge deposit and withdrawal which can cause lots of attention so that's why KYC is been called upon
In the past, the casinos were blamed by the government for harboring money laundering. A lot of them were either closed by the government or went offline, which caused issues for the users who had their deposits in these casinos. That is the reason why KYC is now being made mandatory in almost all online casinos. A few exceptions are there but sooner or later they will also implement KYC. With KYC you no longer are anonymous but as a user, you still have the anonymity factor with other users.
Until now, Money launderer still using online casino to launder their dirty money. This criminal is very pesky because they mix their money like a normal gambler which menas there will be no reason for casino to suspect them as launderers that will make this KYC purpose useless since it cannot catch launderers but only it will just use to delay or freeze someone money when they win huge prize in the casino.
I totally disagree on the use of KYC to counter money launderer since it’s useless in crypto because everything is decentralized and it’s very hard to spot user that laundering money and differentiates it to the normal player.
You might have misunderstood the implementation of the anti-money laundering council's regulations. While casinos might not have direct knowledge of the sources of their customers' funds, they are regulated entities and are obligated to comply with orders from the AMLC. If customers are suspected or proven to be involved in money laundering, the government agency can instruct the casino to close their accounts and confiscate the funds. Casinos don't take actions without a valid basis. That's the concise explanation.