Sure but United (or whoever) chooses to sell them tickets and create those experiences.
Delta has a product called Delta Vacations, run by Expedia. All of these things are businesses decisions they decide to embark on with 3rd parties. They promote the integrations. They don’t have to do these things. I don’t mind if they do, of course, but I have 0 sympathy for them if someone has a bad experience on a 3rd party site selling their product.
If I buy something from Amazon it’s no different.
Exactly, if you buy a pair of Nike's from Amazon you don't go to the Nike website to try and get a refund and then say Nike tricked you out of your refund. The problem is for a lot of people flying is so infrequent and usually a major source of stress that they overlook this fact and it's the airline -- not the cheap prices company they entered into business with -- gets the blame.
If Amazon started to ship Nikes with rips or something in them you’d think poorly of Nike first, because you’d assume they sent Amazon a faulty product.
No, I'd think the 3rd party I bought from through Amazon is shady. This literally just happened to my mother in law. We know the quality of the shoes and have seen them first hand. It never crossed either of our minds that the brand was shipping defective product through amazon.