There seem to be some issues that have caused returns, in the US at least.
One is the 'Poltergeist' effect of the screen relighting itself after software shutdown.
(The FTS Troubleshooting FAQ merely says "this is normal. Don't Panic!"
However, it is problematic for those running automated operations on battery.)
Other problems might be due to conflicting Youtube connection info.
Also, as simply upgrading Wheezy doesn't get you to the necessary Jessie, some people quickly decided their screens were defective.
Many don't want to chance frying the relatively costly FTS (relative to the Pi) and immediately tried for an RMA from the distributor.
For a distributor, returns & customer irritation can be very costly. Just the return shipping will eat any profit on small orders. A distributor has little time for testing, and will quickly conclude they 'got a bad batch'.
The FTS packaging is very well designed, even lavish; perhaps a simple 'Quick Setup Guide' page should have been included.