Amazon has items for less than $10, but most items with a price between $0.01-$9.99 have to sell for $10.00 for their free shipping economics to work. That's notwithstanding the fee that your license to buy, i.e. Prime, cost you.
In San Francisco, if you sit down at a restaurant, take the written prices on the menu and multiply them by 1.5 to get what you'll actually be paying. I don't think it's that bad in Los Angeles.
Further, in San Francisco, if you sign up for $40/mo fiber Internet, it's really $63.50. Somehow Sonic managed to break past 1.5.
The takeaway is there is no hard and fast rule about transparency in pricing. It's all psychological.