The only way for kids to gamble in CS at all is to either steal a credit card, which is obviously not Valve's fault, or for them to have a Steam gift card. If anything is to be done about the children, I think Valve should just 1) require a users to have a credit card on file in order to buy lootboxes, and 2) require re-entering the full credit card details if the user makes several purchases in a short period of time, in order to stop kids who, for example, memorized the CVV of a card already on file in Steam.
Keep in mind that uploading a government ID would have issues, seeing as in the US a driver's license is not universal, not to mention IDs all across the globe. Maybe there's an alternative form of ID that would work that I just can't think of, but anyways, I'm against needing to upload a government ID to access anything unless it's specifically for governmental purposes.
My opinion is that it is relevant... but each to their own I guess.
Regardless, many children most certainly do play Counter Strike.