The "6% standard commission" is charged by brokers who belong to the MLS (Multiple Listing Service) which means that the property can be shown and sold by any broker who is a member of the service, not just the broker who lists the property. The property also appears on the "Houses for sale" listing that the MLS puts in newspaper advertisements, etc. The commission is deducted from the sale price as agreed to by the buyer and seller, and the seller receives the sale price less the broker's commission plus/minus other adjustments such as mortgage payoff, real-estate tax and insurance premiums held in escrow, etc. The broker's commission is generally divided equally between the listing broker and the selling broker in the MLS group, and if the listing broker also sells the property, s/he gets to keep all 6%.
There are independent real-estate brokers who do not belong to the MLS service who often charge smaller percentage commissions or, in some cases, a flat fee, for selling a property, but for the seller, the disadvantage is that there is less exposure since fewer prospective buyers will get to see the property (MLS brokers will not show or attempt to sell the property). In the rare case when two independent brokers (buyer's broker and seller's broker) are involved in the sale, then the buyer's broker will expect his/her fee to be paid by the buyer separately from the real estate transaction; it is unlikely that the selling broker will part with any part of his/her commission to the buyer's broker. For the question asked: What if I find the property myself instead of through an MLS broker or another independent broker? Well then, you have effectively hired the listing broker (whether MLS or non-MLS) as your broker too, and the listing broker gets the entire commission, whether it is 6% or 4% or 3% or $2500.