None of the information here is from polls. It's from SEC information statements and public filings. A privately-held company does not need to disclose revenue and expense information. Try figuring out the profit margins of In'n'Out burger sometime.
That said, landline-only polls have been deprecated for the most part. Half of adults don't have one. Pew incorporates landlines at 25%.
It does raise an interesting point, though - if you are buying online, you have no real need for Amazon. The only thing Amazon gets you is an ecosystem. If every vendor on the planet had a collective bargaining agreement with shippers and a shared marketplace where you could find their products, nobody would need to bother with Amazon.
Which is exactly why Amazon Marketplace exists.
As far as retail, don't forget the very real value of showcasing. Not everything can be bought sight-unseen. Not everything comes down to specs and word of mouth. Some stuff you have to see in person before you can buy it, which is a very real reason stores still exist.
Walmart is now within a third of a percent of Amazon's prices.