Who gets to define the market? Does the "market" consist of only advertising technology platforms, or everything involved in online advertising, or all advertising through every possible channel worldwide?
Because bad behavior tends to scale with company size, not because smaller companies are more virtuous, but because they just have less power to do harm than bigger companies.
Imagine that there were only two companies, and they each had 50% market share in every market that exists. Would you expect either to be well behaved?
You may be surprised to learn that the US corporate tax (yes, that one, the main one we already have and everyone pays) was originally introduced in 1909 specifically as an antitrust measure, to clip the wings of US Steel and Standard Oil.
Of course the best laid taxes always get abused or turn into something else entirely.
There is a reference to this in For Whom the Bell Tolls:
“ Robert Jordan, wiping out the stew bowl with bread, explained how the income tax and inheritance tax worked. 'But the big estates remain. Also, there are taxes on the land,' he said.
'But surely the big proprietors and the rich will make a revolution against such taxes. Such taxes appear to me to be revolutionary. They will revolt against the government when they see that they are threatened, exactly as the fascists have done here,' Primitivo said.”
