20th Century Fox is labeling the BLU-RAY discs with incorrect info in terms of specs

[HDTV1080P]

20th Century Fox has some amazing BLU-RAY's with high bit rate MPEG-4/AVC but I notice that they are labeling the discs incorrectly in the amount of GB's used. 20th Century Fox automatically labels dual layer discs as 50GB and single layer discs as 25GB under the specification area on the back of the case jacket. All the 20th Century Fox discs that I have seen so far do not use a full 25GB or 50GB like the jacket says. Most single layers are in the 20's and most dual layers are in the low to mid 40's that I have seen from 20th Century Fox.
A much more accurate labeling would be to call the disc a dual layer or single layer and not to list an incorrect automatic 50GB for dual layer and 25GB for single layer. What would even be better is if 20th Century Fox listed the actual GB used. Like say 46.6GB, 43GB, 37GB, etc.
If 20th Century Fox is going to label the discs as 50GB or 25GB then they should use the entire disc for high bit rate video and audio with extras instead of just only using part of the disc.
I could give several examples of movies that are labeled incorrectly but one can easily discover this for themselves by placing the disc in a BD-ROM computer drive to check the actual size of the BLU-RAY disc.