If ads were merely about being informative, they would be boring. But ads want to manipulate, so they have to be flashy and appeal to your emotions.
They pollute your mental headspace, and have no place in a healthy society.
Let's ban billboards. And then let's follow that up with a general purpose ban on paid advertisement.
Bribery laws, SEC insider trading/collusion stuff...there's many existing examples for definitions for that, when the law doesn't want something to be for sale.