Ever build a kit? If so, you know it can take a lot of time to build and cover an airframe. Of course, the ARF manufacturers are set up to do it much faster but it I imagine that it still takes time, especially when you have a large run to do.

On top of that you have the boat ride accross the Pacific, customs stuff, getting it to distribution centers, etc.

Then there are the unforseen delays, economic and other issues.

I know the out of stock thing is really annoying but I can see how it might happen.