Proof-of-Age Verification for Steam in AU Now Only Possible Using a Credit Card (ign.com)

"Other methods are available, but Valve is not using them, despite the fact half of Aussie consumers don't have a credit card."

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I'm not sure about Australia, but I know in the US, it's now possible for minors to be issued (secured) credit cards from a joint account, so I feel like this makes credit cards as an age verification solution a bit problematic.