[JCharante]

My solution:

Stop codesharing with marketing flight numbers that are useless. Airlines do perfectly fine selling tickets without having the flight marketed by themselves and they can handle inter-airline agreements without it.

[rhplus]

Customer behavior is key here. There’s perceived risk with the dreaded “Multiple airlines” option when booking tickets, especially for international flights. No-one wants to find out the hard way that there weren’t agreements or reciprocal status or matching luggage allowances, etc. The code-share is shorthand for “we’re responsible”.

[JCharante]

It's safe to assume that if you book on Delta's site then any routings they offer you will have interline agremeent.

Let's say you are traveling from Incheon to Atlanta on a flight with a Delta number. Would you go to the Delta desks to check-in? Maybe... is it a real Delta flight or a flight operated by Korean Air but marketed by Delta? I think getting rid of codesharing would make it much easier for travel novices.

[AnimalMuppet]

It's also shorthand for "yes, you'll get miles in our plan for this flight".

[JCharante]

There are so many agreements for crediting frequent flyer miles that while yes it can help reassure people, there is a million more routes that still credit miles without codeshares to the point where it's useless