As a non american, why arent the other sites getting used? And why does MLS cause this fee structure anyway? Why dont sellers give a 3% discount or cashback to agentless buyers too? It would be in their interest. The cashback would effectively reduce the downpayment.

The buyer's agent handles some matters of the contract like properly notifying the seller of defects found during an inspection by form. There's a process for that that is meant to prevent the buyer from disadvantaging the seller if the house ends up back on the market. There are other things the buyer's agent does, like ours would sometimes temper our reactions when representing us to the seller's agent. She would also let us know when items on the contingency timeline were expiring and what our options were after those deadlines. That's not something I had the time to figure out on my own.