Why does the seller pay the commission for both agents?

Commission is completely negotiable. When listing your home with an agent you will want to discuss this with. If you so decide to not offer out a commission to a buyers agent there are some concerns with. If a buyers agent shows your home and there is no commission offered, then they will ask the buyer to pay for the commission. If the buyer doesnt have it, they cant make an offer on the home. If they do have it and other sellers are offering to pay the buyers agent then the buyer interested in your home will often offer less for the home to compensate for this charge that they will have to pay. As a sell you dont have to pay for anything or accept any offers you dont want to, though just consider why they may be in place as a benefit for both buyer and seller.