There is a reason why Google Play recently updated their pay screen pop up such that users have to click one extra time before actually going into the password landing to confirm payment.
Previously, their TOS were super unclear but you are correct to say that it is a policy rather than legal obligation.
In Canada, in-game micro-transactions are now considered a branch of gambling and the Government has started to produce various pamphlets and updates on official websites to promote awareness. Soon, unless there are major gaming lobbyist pushing against this, it could be possible for similar legislation or, my guess, Alcohol and Gaming Commission could take over this portfolio. There’s just too much revenue flowing down this stream.