Each similar search Google can avoid re-running saves them compute resources and therefore money. Google's as-you-type search suggestions encourage some significant percentage of users performing a query to accept a search suggestion (or suggestion that aggregates multiple searches) that match exactly with searches that were already run. Google can just re-return the results.

The autocorrection and removal of terms accomplishes the same thing.

While I think these measures may be partially to help users, I think they're actually mostly cost-saving measures on Google's part.