I have the sense that being a "captive" customer to a single carrier, or two carriers at most, is a predominately American problem. Here in Houston -- a huge c

I have the sense that being a "captive" customer to a single carrier, or two carriers at most, is a predominately American problem. Here in Houston -- a huge city in the middle of the country -- it is far, far easier to fly United than any other carrier for any long-haul route. Southwest is an option for close US locations, and that's great, but United is what you're using to go to either coast. Sure, there ARE other airlines here. There are LOTS of them. But if you want to go to the UK on something other than United, you better be going to wherever that other carrier goes, because you won't have a lot of options. (EG, Singapore flies direct to Manchester, but that's it. Emirates flies to Dubai nonstop every day, but has no other legs in Houston.) In smaller places, the choices are often starker.