But buyers do not treat the much cheaper homes as undifferentiated commodity items (like paperclips and crude oil) because each house is situationally different.
E.g. One house may be listed for $250k and is on a desirable corner lot but also needs a new roof and kitchen remodel. Another house is $280k and already has a new roof and updated kitchen appliances and is also 10 miles closer to the office to cut down commute times but costs +$30k more. The combination of tradeoffs (location, condition of home, price, etc) to be matched to each buyer's priorities is what makes homes -- even the low end homes -- resist becoming commodities like paperclips. In a box of paperclips, you can randomly pick any one and you don't care. Picking a house doesn't work like that.
Part of the real estate agent's job is to downplay the negatives and highlight the positives of each house they sell. I don't think that work is worth the 6% commission but regardless, houses are not commodities to the point where most buyers & sellers are comfortable with no intermediaries in the transaction.