I hate microtransactions, but it isn't the government's place to get involved. There are ways for parents to limit or block transactions altogether if we're worried about children buying stuff.
The only way to stop this practice is to not take part in it, vote with your wallet so to speak. But people spend their money on stupid like a new Fortnite dance or a pink dildo accessory for their Roblox character, devs make tons of money, so it will continue.