What I mean is, if Agency A managed to secure a client for Freelance Model B, without B having to do anything, then A gets the commission. Agency C gets zero.
If a client knows of A, B and C, he can choose to go to either of them. He then pays the commission to whoever he goes to.
A serious client may not necessarily go to B direct for cheaper prices. He may go to A if A is a reputable agency. If B some how pang seh, and he went to B directly, he will have problem getting compensation. If he went to A, he can sue A for breach of contract and he will have better recourse.
This is for the so called "freelance" agencies.