Just In Time Contextual Offers

Flight booking websites and mobile apps push great discounts to users' inboxes and mobile devices, attracting them to make a booking. Users landing on such a website/app, end up scouting for discount that more often than not, disappears the moment user lands on that website/app. The users leave disappointed and angry.

Google Flights does exactly opposite of that. If a user attempts to book a flight, the app suggests that there is a better discount on a different date, if the user is flexible with dates. The message, Return 1 day earlier is a decent warning if a user chooses this option. 

Google Flights website also allows users to track prices using Track Prices feature. 

If not for contextual offers, what else does a user need?