Real estate agent commissions were NEVER standard anywhere in the U.S. If an agent ever said they were they were either ignorant, used a poor choice of words or were fraudulent. There are commonly found percentages however such as 5 or 6%. If the commission is say 6%, the listing agent splits the commission with the buyer's agent. Each agent splits then their share (3%) with their respective brokerage. Before tax percentages might be 1 to 1 1/2 %.
The reason buyers agents don't charge a commission is because commissions all come from the seller...
The buyers agent (mentioned above) may be a very nice lady, she was paid however and paid well for representing you as they buyer. Her commission was paid directly from the seller via escrow out of sales proceeds.
These days it is harder to sell a home and agents spend more money advertising as they need to. Try to use a well experienced energetic Realtor who specializes in your area and who lives close by. Nothing worse than having an agent commute just to show your house. You know they won't be too eager when showing requests come in if they have to travel.
When discussing commission with a prospective agent, ask them what their advertising plan is and what specifically they plan to do to market your home. The gravy days (2000-2008) of simply listing a house on the MLS and waiting for the phone to ring are over. You need a clever, smart, ethical, market savvy and hard working person to get the job done these days.