Google earns 92.42% of those search results, by being better, at least subjectively, than their competition.

Now if you listen to the various whines of said competition, Google sure looks objectively better too, using extreme personalization to drive more relevant search results to their userbase.

There is no pressure there. If alternate search engines were subjectively (not even objectively!) better, people would switch overnight. After all, they are just a click away.