This is the most sensible solution to this problem I have read on HN in the 2 years I've been here. Think of the positive effects taxation would have: no whack-a-mole for every loophole the industry will find. No single fines after costly court battles that are basically pocket change for Zuckerberg et al. Adherence to polluter-pays-priciple. Make it so that if they stop advertising, the tax expires. Use the tax money for better infrastructue. Make the tax progressive - the more ads, the higher the tax.

Added benefit: even adults will be less exposed to addictive material.

What would be the cons of this?