From the seller's perspective, the fee is the same. The seller wants a piece of property sold and is willing to pay a certain commission and signs a contract to make that happen. They're paying for an outcome not an input, effort, or number of mouths fed/hands out.
Whether it sells to Abel who has a traditional agent, Baker who has a buyer's agent, Charlie who uses an agent who happens to be at the listing agent's agency, or Dave who doesn't have any agent at all, doesn't change the seller's commission charge, which seems roughly reasonable and aligned with the value the seller received.
Whether it sells to Abel who has a traditional agent, Baker who has a buyer's agent, Charlie who uses an agent who happens to be at the listing agent's agency, or Dave who doesn't have any agent at all, doesn't change the seller's commission charge, which seems roughly reasonable and aligned with the value the seller received.