Those who are persistent can always eventually find someone willing to sell their property for 3%. That isn't some online discount scam, that's a local realtor with local billboard ads, regular newspaper inserts, and a respectable web presence who is will to take half to do this job. Maybe you're in a hurry, maybe you like gold-plating, maybe you have to use your sister-in-law as a realtor, but if none of those circumstances apply then a 50% discount is well worth pursuing...

Of course it's because of all the efficiencies you mention. Their job is significantly easier than it used to be. They can afford to charge less; they just forgot to tell the general public about that.