What are the determining factors in preventing users from price-tracking a title?

[J___T]

I'm guessing nobody answered my question on how to edit a page to enable price tracking because nobody knows how to do that as it's not intended to be an editable function.

So why are some titles price-track enabled and others not? I just came upon a new pre-order title for a film I saw as a kid and remember enjoying that has no option to price-track.

This after missing out on a spectacular Black Friday deal on a very special set because there had been no opportunity to sign up for price-tracking alerts on that set even though I was logged in to this site at the time of the deal.

So what are the determining factors in choosing to prevent members of this site from price-tracking certain titles despite that generally being an available feature?