This is not technically true. In all circumstances the BUYER pays all of the commission fees. It comes out of the sellers proceeds, but at the end of the day the buyer is paying this fee. (through their mortgage, cash payment, whatever)
The basic deal is this: As a buyer you are paying a commission. If you do not have an agent, the SELLER's agent gets all of the commission. The SELLER's AGENT has a fiduciary responsibility to represent the SELLER, meaning their legal responsibility is to make sure they get whatever they can for the seller.
If you employ a BUYER's AGENT, their fiduciary responsibility is to YOU, meaning they are legally responsible to you to make sure you are represented properly, both financially and legally, in the transaction.
At the end of the day, you are paying the same commission whether you have a buyers agent or not: meaning you need to hire one that has YOUR interests at heart and not the seller.