it’s not that Google, Apple, Facebook, and Amazon aren’t monopolies. They absolutely are.

In its response, Amazon said it "accounts for less than 1% of the $25 trillion global retail market and less than 4% of retail in the U.S."

Do these numbers qualify as monopolistic?

Much turns on how you define the market, and if we suppose that Amazon does not have to compete with physical stores, then we can look at online retail. I can't find any source that says Amazon controls more than half of U.S. online retail. The highest figure, 49.1%, is an estimate of "e-commerce" and may include Amazon's considerable revenue from web services in addition to retail sales. Most sources show Walmart, eBay, Home Depot, Wayfair, Best Buy, Target and Costco providing competition for Amazon. It's not that hard for a shopper to compare prices online.

In the past, a monopoly could dominate a local market by selling kerosene at prices lower than anyone else could match (alas, poor customers!), and negotiating deals with local railroads to keep the competition out. Now online businesses have to compete with the whole world. What stops DuckDuckGo from competing with Google?

Is Apple a monopoly in smartphones, their honeypot? I don't see it.

As for Facebook, someone might argue that it

is obviously the largest social network and its value, like any other network, grows as the number of users increases. It also grows as the amount of information it holds increases. (Finding your long-lost friend's page is pointless if it says nothing about them.)

In other words, social networks, unlike instant messaging, require a higher level of "investment" from users. They must not only create a list of "friends" but also spend time and energy providing information about themselves.

Alternating between multiple social networking sites entails a greater cost than switching between instant messaging programs. Is the economic "gain" of a single social network great enough to for the market to naturally eliminate all other rivals? Evidence suggests a rosy future for MySpace.