You're right, but I don't think this is quite what the quote is referencing. If payment details are stored and kids are merely presented with a colourful popup

You're right, but I don't think this is quite what the quote is referencing. If payment details are stored and kids are merely presented with a colourful popup confirming they want to spend $99 for 2000 gems, it doesn't seem like a real transaction to them (putting aside the fact most kids have no appreciation for the value of money).