Percival P. Cassidy wrote:
Perhaps things vary from state to state, but when I was telling our
realtor here in Michigan about my brief experience as a real-estate
salesman many years ago in another country and mentioned the sliding
scale of commission (5% on the first bit and decreasing from there on
up) used by the real estate agents' organization there, he said, "That
sounds like price-fixing, which is illegal."

The sliding scale is common in California, as is non-percentage based,
flat fee commission.

Only a very naive seller pays 6% on a house more than $200K or so.