Yes, there are taxes and the operator withholds and pays them himself. In the annual declaration, you can write only part of the net profit after taxes. I think that not taxing winnings will be a serious loophole for money laundering through, for example, fixed matches, for example, you can spend large sums. And so with The state has minimal control over the players.
This isn't totally true, there's no time that not tasking winning is going to be a loop hole for laundering, one of the measures most gambling sites have deployed to check for laundering is in the aspect of making sure to wager almost all deposit and so it's difficult to claim laundry on a win in most cases except in situations where the casino may be directly involved then there may be manipulations to claims of wins even when there was Never any in the initial but for a very credible casino where a proper investigation can be done into the wins, the chances of laundry becomes very slim and close to impossible as the casino having their reputation held high, they wouldn't be willing to allowing such go through their casino without it been treated s it should be involving the authorities. Winnings can not be seen to be a laundering means especially for sports games where the casinos have got almost no control over what ever it is that happens with such.
This is possible to do at online casinos, but at psychical casinos this is not really possible, still I find the explanation about those taxes being a form to stop money laundering as not believable, as someone that is doing so with that intent is without a doubt willing to take a loss in order to make that money seem legitimate, besides once a person reached a high enough amount of money, they could start their own casino and do this more efficiently, which is exactly why modern physical casinos were created on the first place.
Taxation of gambling winning is most seriously in few countries and sometimes in some regions, the government does not have the tools to specify who is really paying tax and who does not pay. There are so many ways people are diverting taxation up to now and it is very difficult to track. Gambling winning has nothing to do with taxation on a norms but in some countries, the government would want to get there feet on every corners to know how is paying and who is not paying. Even in physical casinos, gamblers are still paying there tax when it comes to winnings that is why it will be very difficult not to pay tax on every winnings.