Imagine you booked a flight directly on United.com instead of using Orbitz because you wanted to get the extra miles on your frequent flyer account. You ordered the ticket weeks ago and the flight is coming up soon, but you need to look up the flight number, time it is leaving/landing, and other sorts of information.
Here's a quick usuability test: Take a look at united.com (244kb jpg) and tell me how you'd expect to retrieve info on your upcoming flight.
hightlight this text with your mouse for the answer:
None of the forms will log you into anything that will get your answer. there are 90 links on that page, and the correct answer is one of them. Down in the lower left, there's a link that is bold, in the middle of a list marked "My Itineraries". Clicking that takes you to a page about itineraries, making you decide if you actually want "All United Itineraries" or just "United.com Itineraries" as if you should know the difference (do they think we're all travel agents that are hip to their lingo?). Clicking one of those will take you to a login form, which then finally, gives you travel info on your upcoming flight. That's the only way to get the info from their site.