Actually, film is stored at 24p (on BD and HD-DVD) because it originated in that form (24 frames per second) and this takes up less space than 30p (24 film frames + 12 duplicated fields created during the 2:3 pull-up process)!
Yes, but I was contrasting that with DVD. On DVD no redundant information is stored for 24 fps film material either... but rather than storing the film-based signal in native 24p form, on DVD it's parsed into fields and stored in "48 fields per second" form with flags to identify field pairs that represent frames... 3-2 pulldown instructions are also included for MPEG decoders to produce conventional 60 Hz NTSC output.
But the primary difference that I was pointing to was that to generate progressive output from DVD from film material you have to rely on proper flags to identify frame pairs or you have to recognize 3-2 cadence after MPEG decoding. With HD DVD and BD, however, the actual "frame" is stored as a frame rather than split into fields so no additional processing needs to be devoted on the decoding/output side to generate a progressive output (but again, in both cases of DVD and BD/HD DVD, film material is stored without redundant field/frames to made the most efficient use of space).