Actually, they typically get 1/2.

Many brokerages get nothing except a flat fee per transaction and a "desk fee".

Some take nothing at all if you're a top producer and refer your clients to their title and mortgage operations.

HomeSmart is the largest, I believe

Is this true in high-demand, low-supply markets? I've found the brokerages get much more greedy in these situations. See: Seattle, San Francisco, NYC.