It makes sense for there to be only one iphone production line, in the same place as all the factories that make iphone components - shipping the components around and having multiple copies of the production line would probably be more wasteful. That's not really a concern that applies to roses.

Yes, since roses can be grown almost anywhere, and they are 100s of replacement for a rose.

In theory bananas can be grown anywhere, but I believe biology has other things to say.

Bananas aren't flown though. They can be grown in many places, it's just the current supply chain for them is most cost-effective.

Some bananas certainly are flown, although I don't know the proportion of the total.

They were loaded into a flight I was on from Costa Rica to Paris.