Yes, and you can do nothing about that data that they get - the booking number, name, etc. That is not the data I am worried about. When you have an app on your smartphone, any app at all, you are the product. That app is harvesting analytical data about you - your location, how long your are there, what email servers you use, who your contacts are, what pictures you take, what you buy, what other apps you use, all sorts of stuff that is none of their business. They then sell that data to the highest bidder, people that use it for marketing, insurance purposes, investigations, etc. You agree to these terms, many of them hidden in legalese, when you download the app. Many of them claim not to do this, but how many times has Zuckberg or Google been exposed for the same, even when they said they are not! Best to avoid any app unless absolutely necessary IMO.