As an Android developer with a couple of apps in the Android market, I don't really agree with this, at least for the type of apps that travel companies would produce. For simple user interfaces, developing an app using the simulator, then testing on one or two devices, is quite sufficient. It's what I've always done, and have had zero complaints from users on this.

Games are of course different due to their heavy user interface and GPU requirements, and yes the fragmentation of the Android platform may well be a problem for game developers.

Of course, we then need to differentiate between reality and perception among management of those companies commissioning apps. If they've heard that Android is fragmented they may well be less willing to comission an Android app, regardless of what the reality is. Such is business.