Except it's actually more nuanced than that, and this is important... the client actually has a contract with a brokerage, where their agent is actually a sub-agent. The commission fee goes to the brokerage and in many cases the agent doesn't have the ability to negotiate it with the client (despite being an independent contractor). When the commission is paid, it is paid to the listing brokerage and then split out according to the agreement - some to the listing agent, and then in many cases to the buyer's brokerage who then splits it with the buyer's agent according to their agreement.

This is all important because there's a layer of legalities and agency relationships that the public completely ignores, but is relevant if we're going to have a conversation about commissions. It's also relevant because some states have begun to change their laws to be more in line with what the public thinks happens, which has its own weird twists.

*Brokers and lawyers in the audience will probably say I'm still handwaving away some nuances here regarding agency laws. Mea culpa, I'm trying to keep this simple.

Except in a for-sale-by-owner scenario, where the seller is not using an agent. In those scenarios, it may be necessary to agree to a fee paid directly by the seller to a buyer's agent. 2-3% is typical. This is not always necessary - some buyers will not be using an agent either, but it is not rare.