I think gambling sites only want huge profits with the number of members playing on their sites, regardless from of the data used for Kyc real or fake so far, because their dont care about age limit rules , I think to prevent minors from gambling should be the main responsibility of parents at this time, although it may interfere with their activities but parents should take the time for regular supervision, such as Monitoring children online activities regularly can be done without must to stop working, like checking browser history and using monitoring tools if possible.
For some small sites maybe things like this will not be too glanced at but for some large sites I am quite sure that in the end small things like this have been noticed from the start because after all they don't want their good name to be tarnished just because of some irresponsible people to make their image bad in the eyes of other players or governing authorities from the government because in the end for some large sites there must have been more glances from the government in office where they are.
Although things like this must still have leaks but in the end things like this are also included in the improvement agenda so that T&C is sometimes updated regularly.
As for those fake sites or impressed new sites, the most important thing for them is how to get customers to play on their site and it cannot be denied that rarely do they care about whatever happens, the most important thing is that their site remains crowded with visitors.