I never knew, just recalled previous forum threads that had said VUDU didn't have CC/subtitles yet (has it been supported all along, or an addition somewhere along the way like with HBO GO?).
The VUDU support article about subtitles
is dated 10/1/12, so they've only been available for 11 months.
As you pointed out, I guess I haven't run across the "Subtitles" label often enough to take notice, plus I think I'd only ever tried the "Watch Trailer" instead of "2 Min Preview".
The trailers never have surround sound or anything fancy; the previews are best for testing.
I wonder why the relatively limited selection of titles with CC though, wouldn't they get it from the same sources as Amazon, Redbox Instant, Blockbuster, etc?
There's got to be subtitle ("timed text") assets developed for most video and certainly movies once they get to disc and I should think that they'd be available to VUDU, Netflix, Amazon, et al. The streaming services have only slowly given in to legal pressure from disabilities activists and VUDU has been slower to respond than most. Netflix has 90% of its library captioned; looks like Amazon has only a tiny subset of theirs captioned. There wouldn't seem to be any kind of filter for it in the VUDU players.