When I worked in real estate, it was common for agents in the Seattle area to not show homes that had a reduced commission unless the buyer really wanted to see it. Agents will tell prospective sellers that a reduced commission will restrict the number of people seeing the home. Agents won't spend as much on flyers and advertising on a reduced commission. And if doing a weekend open house on a listing which if sold will bring the listing agent 3% or do an open house on a 2%...which one will these narcist people hold open? Right.
The commission percentage should be negotiated by the seller and the agent which is a free market principle in practice.
On the surrface a higher percentage sounds great, but the actual profit is what they should look at. Would you rather sell a $100,000 house for 4% or a $200,000 house for 2% ? I think flat fees are they wave of the future.