Re: If search is a contestable monopoly
Then so was Windows and so was Standard Oil. After all, you just needed to drill your own wells, build your own refineries and open your own network of service stations to sell the gas.
Windows has some level of lock-in, in terms of software that runs only on Windows and the cost of re-purchasing software for another OS. Where their monopoly becomes a problem is where they actively try to persuade people to not develop for their rivals.
Standard Oil has a massive barrier to competition in the form of capital required to purchase land and drill wells.
In contrast, how much does it cost to host a website?
The investment to compete with Google on search is massive. Economic barriers to entry are still barriers.
I could write a (very crappy) search engine today and put it on the web, thus competing with Google. It may be tough to take market share from them, but that's because they're really good at what they do, and that's what they would risk if they engage in dodgy behaviours. Bing, Yahoo, etc show this. If they had a better offering, people would use them in preference to Google.