The other countries strictly implement the rule that they do not allow a minor to enter a casino, whether it is an online or land-based casino. I also don't see anything wrong with this step they are taking.
And this kind of implementation that a country is doing is really good because it only shows a real concern for minors, and it is good to see it being implemented in all countries that are legitimately allowed to operate gambling in each country, if that is where it stands.
Under age gambling is what both online and offline casinos don't joke with and some times why the government are so strict on gambling licensing os because of the KYC implementation which will help to expose any possible under-age registration and from the document verification you will be sure to be able to cash up with any of such possibility of underage.
The cosino have the sole right to request for verification from the gambler anytime they feels that the gambler may be an under age and since government laws already cover that aspect is much essential for casinos to comply with that law at all time to avoid sanctioning.