* sending my ticket to my place
* checking my identity at check-in
And then, addressing me as "Mr. Smith in seat 14C" or asking me what I want to drink really isn't a problem. Checking if I have connecting flights can be done without knowing my name. So, as GDPR dictates: everything else must be opt-in.
Not always. Many airlines (for example, American Airlines) will protect your connection even if you've purchased two separate tickets. And they'll do this across their entire OneWorld alliance of airlines, not just within the company. But unless you have added a frequent flier number, the airline needs multiple matching information (Name, DOB) to be able to make the link between your two reservations automatically. Otherwise, they would be unable to proactively rebook, hold the connecting plane, have someone meet you at the gate to rush you to the next gate, etc.
> Sorry for the inconvenience ... Note that you will no longer be able to connect to the flight you selected [AF1234], please follow the link to reschedule with [Air France] https://brokenconnection/?nogo=UA4321&connection=AF1234
> [...]
Wow, I'd never heard of this. How would this even work? I thought they always connections happen in a reasonable time, hence why you need to book them as connections... otherwise if you book impossible "connections" separately then do they just basically agree to give you compensation despite you not even giving them a chance to check if the connection was possible?