Simple: because the flight was sold to you by ZZ, this is now ZZ's problem and they will have to find a way to make you whole, either by rerouting or refunding you. That fact that YY happens to operate the flight isn't really more relevant than that Boeing happens to have built the plane.
Note that if YY's collapse is sudden, a lot of people will be in the ...
The issue is extremely complex and it might need a court decision.
To begin with, now that you no longer get a paper ticket most people have no idea about who their issuing carrier (also known as validating carrier) even is. And your issuing carrier is the only one who can help you. (With an emphasis on can, not must, read on.) If you look at a paper ticket ...
There is one way to know for absolute sure. As you are checking in with a human, who is preparing your bag tag, you ask "do I need to interact with my bag at [transit airport] or will I just see it again at [final destination]?" They will give you a definitive answer.
However, you may not plan to check in with a human (many kiosks print bag tags ...
An airport makes its money from fees charged to user airlines. These fees include (but are not limited to)
per passenger handling fees
baggage handling charges
Whether there is a specific charge for a dedicated area in the check-in hall, or a per-hour charge for the use of check-in desks, or the fees are rolled up into some ...
The simplest, most effective method, is to read the airport code shown in the luggage tag:
It could have one airport code, and that's where you will pick up your luggage:
Or, it could have multiple airport codes, check the "To" airport code, that's where the luggage will be taken to without any manual work from you:
It is that simple.