Perhaps you’re viewing the situation from an urban perspective?
Much of the country is rural. I know I am. Recently a part I needed (but, not immediately) was $250 from the local car dealer , but they don’t stock it.
The part was available as a Doorman after-market item for $239.99 (minus some discounts) at my local Advance , but not in stock.
Rock Auto stocks the same identical doorman part (and part number), life-time warranty, in stock. I ordered with basic shipping and got it in my mailbox in 3 days for $107.44 total, including shipping! I installed it the day it arrived.
More savings… A round trip to town to an auto parts store is 40+ miles, the gas, the wear and tear, and an hour or so of time.
Rock Auto rocks! I use them often. I doubt amazon will set up a distribution center near my middle of nowhere, but hey, who knows?
The part was not available close to that price on e-bay or Amazon, believe me I checked.