Technology has moved on, and there are now ways to do this. They are already being tried out in the online banking and finance sector. These are mainly devices that connect via USB and check the bank card for example, or even things that CANNOT so easily be stolen or "borrowed" by a minor, such as fingerprint or iris scans.
If governments have their way, such as the UK getting a national database of EVERYBODY's DNA, fingerprints, iris scan, etc - there will be a SECURE way not only to check that the person sitting at the PC is the one who registered the account, but to check the very ID of the player in the first place, with no more of the "send documents, forms, etc" that is now needed.
IF online casinos potentially regulated in the US are able to show they CAN strictly enforce prevention of underage gambling, and can prevent ID fraud when registering and playing, then maybe they can convince other senators to join the cause (raising more TAXES of course - and in an "ethical" manner, not giving players what they want

).
Bookmarks