i don't understand, how did she get away with never having to show her tits in a movie?

What are you talking about? She was explicitly nude in Into The Night, pretty much showing everything in a sequence. She was also nude in Tequila Sunrise.

She would have shown them in The Blue Lagoon and Disclosure had she not turned the roles down. Paul Verhoeven wanted her to star in a kinky pirate movie called Mistress of the Seas.

If she did show her breasts, the men on this board would be calling her a whore. If you want to see boobs, watch porn, leave this classy actress out of it.