My guess is, that an average developer, who is familiar with the platform, spends a similar amount of time for doing the same thing no matter what the platform is. It's just the case that there are more developers for iPxyz platform, making you to think that the development itself is faster. Not being able to sell stuff will keep commercial developers away.

Now, I haven't tried the Apple stuff, but I would guess that their environment has a less steep learning curve. The FOSS community is too happy to give the RTFM to n00b questions, only the documentation for open source stuff is often quite obfuscated. Also lot of people seem to forget that googling is non-trivial when you don't know the name of the thing you're looking for.

Personally I don't know why someone would like to develop an iPhone app anymore.

I mean, after several years and 140k apps, what's left to be done? There's an app for that already.