The 've is understood.

No. Because seen in this context is usually used in an inappropriate tense, where saw would be grammatically applicable, using the past participle form instead of the past. If it was simply a matter of dropping the supporting/qualifying have or -'ve within the proper tense it wouldn't be as much an aberration. Using seen instead of saw in this context is akin to saying I eaten that, which, of course, requires the supporting have, instead of I ate that. But, as you point out Faldage, the fact that folks have taken to lazily dropping the qualifier in the past participle form of seen has helped it to sound "right" through repetition, and thus to wash over into usage in the improper tense as well.