IceBear, you sound frustrated. I don't know if my interpretations will help, but I will try:
Helpless (bound, held, sleeping, paralyzed, or unconscious) DO get a Reflex save, but their Dex is effectively 0.
Bound (helpless) characters cannot use Evasion. Thus, sleeping rogues cannot use Evasion against a Fireball, but MAY (if they're really lucky) succeed at a Reflex save.
Snatch (a Dragon feat) specifically addresses saving throws and breath weapons, but does not otherwise impart a condition of Helpless on the character who was Snatched.
Two ton rocks don't need to roll to hit things in their way, but neither are characters allowed a Reflex save to escape damage. This is the "crushing wall trap" referenced in the DMG. Characters MAY have enough hit points to survive the initial crush (rationalize as desired), but the subsequent rounds may get messy if the character cannot move.