One was that I tried to do it on an Indian site, Make my trip, and the email address for privacy they had on their site did not work. [This one has](https://www.makemytrip.com/legal/privacy_policy.html) email id listed as 'privacy@go-mmt.com' but the mail bounces when sent to this id. So, they complied in the name only, and wanted to see if others did as well.
second, I am curious as to what data these guys store on their customers. We saw the kind of data spotify stores, which has a lot of depth. If travel companies are storing a lot of data, this could give me another data point whether or not to use the sites in incognito mode (they dont function if you disable cookies).
Also, the more pertinent question is that if they have a lot of data and really rich user profiles, why have the OTA sites not evolved much in the last six seven years? (the new ones try to, but I think they rarely raise a big round in B2C unless they are doing something like Airbnb. Probably because of the consolidated market.)
Having all the same data means they all follow the same set of steps, present the same filters, and so look and feel very much 'the same' because they are.
The filters and steps are more a part of A/B testing and Conversion Rate Optimisation, which you expect any online website to do. That does not even use any of the user data for doing that. The filters are standard - more like if others are giving it, we should too, and they get all the possible flight information about a flight from the airline/GDS. Also, when I said evolve, I meant all of them look the same as they did in 2013 - with minor differences here and there. No one even looks to buck the trend, maybe by offering personalized suggestions first. Had Facebook/Linkedin been doing flight bookings, could have been really different.
The use of data comes in use cases like: if I am looking for a flight, show me something optimized for variables I usually prioritize (esp if I am a repeat user), not a generic way of eliminating bad results, or just one sort option. Similarly, for hotels, show me the kind of rooms I have booked before, or the ones others like me have booked (item - item recommendation) which does not happen right now. With destination suggestion, a feature quite a few OTAs are trying to incorporate, tell the places I should go to. That does not even happens with experience/activity searches either, even when those are made on the same website.