Region Indicated on Case Not Always Correct - Why?

[MichaelYYZ]

Why do some studios list a region code on the disc case, when the disc is in fact region free?

I've got several films (e.g. MGM, Fox, HBO) which indicate that they are Region A, but they play perfectly well on my multi-region Blu-ray player when switched to Region B or C. Others (e.g. Criterion, CBS) would not.

Similarly, I've got a few Region B discs which would play if my player is set to Region A or C (e.g. Shock/Fox, Divisa/Filmax) while others (e.g. Network UK) would not.

Why are some studios listing an incorrect region code for their films? Perhaps still trying to dissuade people from other geographic zones from buying the discs without actually bothering to encode the region coding on the disc?

Thank you for your insight.