Whats the relevance to have the query time, e.g. "0.26 seconds" or the count of the result set, e.g. "About 8,96,000 results" on Google Search Engine Results Pages (SERP)? Does this anyway help users or is it just a KPI. How many of the people watch this data? You don't find this on Bing rather!
It's a selling point. By showing that the search results were acquired in a short amount of time, they're advertising the speed and efficiency of their search algorithm.
This doesn't really affect the majority of users in a meaningful way, but from a UX perspective, they choose to show this off because it enhance (in a subtle way) the trust factor inherent in the results. By saying "returned in 0.26 seconds", they are implying that there is a mechanical reliability and efficiency to the process, which inspires more confidence in the results. This is the same reason they display the number of results found, even though most users will never see the millions of results returned by most search queries.