I think the issue with Supcom not displaying Cost values of units was because the game was largely based off the numbers. And with frequent balance changes there no guarantee the the released unit costs would be the same as patched unit costs. As far as errors go, Yes errors happen, but they are not always on the devs end. Sometimes it's a printers error in the transfer process. Things like that happen.

As a child i always thought a good manual defined a game. Just look at the manual for the original Red Alert, or the game in the Warcraft series, those are like novels!(not saying GPG needs to make a novel) but a level of detail above everything else really goes a long way... especially when your manual is a tech tree...(looking at you Forged Alliance) Of course it could be argued Print and production costs of detailed manuals eat into the profit figures of a release, and as an avid lover of money myself I couldn't fault anyone for that. -unless it were just a tech tree

The manuals aren't finalized until very late in the beta anyway, once everything stops fluctuating. As a sometimes unwanted side effect, that also means the game itself becomes locked down because the manual needs to match the release.

And today, publishers try to save costs.. printing those "book" manuals isn't cheap. Even the game boxes themselves are something like half the size of what they used to be. C'est la vie.