Why is time-coding optional on DVD's?

On some of my DVD’s, the extras don’t have any time information while you’re playing them. The display is just blank, and you can’t see elapsed time or even duration. The movies almost always have this info though (unless they’re really cheap).

Anyone know why this is even allowed? DVD seems like a pretty tight spec and this seems like an obvious thing that could have been avoided.

If you press the Display key, can you see a title/chapter number?

Total WAG: Time coding might only be present for clips that are part of a title. Notice that menus don’t have time codes either, even when they’re animated.

On certain DVDs I have with this problem, I can definitely say there is title & chapter info, just no time info. For me, the most annoying aspect of this is that I can’t look to see how much longer the featurette is going to last. I find that insufferable.

The way any particular DVD behaves is totally determinded by the disc, not the player. Essentially, the disc itself contains a bit of microcode which the DVD player loads into its OS when the disc is inserted. Thus, the way in which any one title can (or cannot) be viewed is controlled by the people who author the disc.