[qpsk88]

> I think the current situation, where exchanges basically "tax" those who take liquidity and reward those who provide it

I like you explaination, but exchanges are nowadays mostly private companies so the 'tax' goes to shareholders and not to the state.

[tomp]

Exactly, which encourages competition - exchanges can either reduce this tax (earning less per trade, but encouraging more volume), or maybe even increase it (rewarding liquidity more, and so improving the trading process).

[qpsk88]

Point taken, but competion is not a value by itself, tax money is.

[tomp]

I disagree, I think orderly markets are the goal. Ideally, the government should collect as little tax as possible, while providing rules that promote the good (e.g. competition) and discourage the bad (e.g. violence, externalities).