Purchases are only taxed when you're paying with real money. There was probably always tax. Before when we could pay with points, while tax wasn't taken out of your points, you paid tax when you purchased the points. Now tax is taken when you purchase the item, like a game.

For example, when you buy a card of points from a store, you'd pay around 6% tax depending on where you live. When you redeemed the points for digital content, there was no tax involved.

Now when you purchase digital content with real money, there are no points involved, therefore the tax is being taken from the digital content purchase, and not from a card purchase.