I think it's the standard that is set by the original creator of the UI widgets available on the platform, in this case, Apple vs. Google. I'm an iPhone UI designer/developer and you can make a really nice looking app without doing any custom design work just by using the widgets that Apple provides. A good example of an app that was nearly all stock is Tweetie 1 for iPhone and it won an Apple Design Award. Apple has…
That doesn't excuse the apps that actually write an entire UI from scratch. As I mentioned before, the CNBC app is all custom UI, beautiful and mostly entirely self-contained. However, the android version is a POS thats essentially just a mobile webpage. Built in OS UI is not a factor here. I suspect budget isn't either. Edit: Here's the link to their Android app. The screen you see is basically the whole app. Click…
There are, however, so many possible reasons why Android versions get the shaft that it's nearly impossible to say why any given pair of apps are so different in quality. It could be that it's easier to find iOS devs that really care about UX and polish (lots of self-selection going on here, similar to Mac/Windows third-party devs). It could be that a company asks their iOS dev to knock out an Android version, when they're not competent at developing for the platform. It could be that the folks in charge of getting mobile apps made for their company just like iPhones more (not a stretch, given demographic differences) or see them as more hip or marketable and funnel more money that way. Or, it could be that, after spending lavish amounts of money on the iPhone app and seeing it not set the world on fire, they scale back to merely "establishing a presence" on Android instead of making the same effort.
A lot of these behaviors wouldn't surprise me, particularly from companies whose primary business is not creating software.