From what I have heard
on the Ferrari one, it's a combination of factors -
- The ride hardware was finished long before the theming, so it sort of took 'twice as long' to even build it.
- It has a number of special elements which have been difficult to commission (perhaps due to it being a prototype for SFX has made this a bit tougher).
- The theming itself is quite elaborate and has some 'show' scenes, which have also taken extra time to dial in.
- SFX have changed bits of the design along the way which has meant other modifications have to be done.
To be honest though, I don't know if anyone has every publicly shared any specifics. I've heard these things from people who do know some of what's going on, but not the full picture.
Given the country, I wouldn't be surprised that there might also be some commercial delays having an impact too.