American Muslim parents trust their kids to do the right thing and let them run their own lives.Please note that this comparison is made with Muslims living elsewhere in the world.Quran does not expressly forbid Muslim women marrying non-Muslim men and neither prophet has expressly forbidden it.
Muslim scholars unanimously agree that dating is forbidden in Islam.
Guarding the flock is a human trait and no tradition wants to lose a member of their tradition to the other, whether you are a Hindu, Christian, Sikh or a Jew, Republican, Democrat, Libertarian or new, indeed, any tradition for that matter.
Muslims are no exception either and there is no need to beat up on Islam for a deficiency in comprehension.
In the traditional societies parents rightfully feel responsible to guard the happiness of their offspring, where as parents in North America are learning to believe that their kids are independent and know what they want in their lives, and will find their own happiness.
Ultimately they have to live their own lives and you cannot babysit them forever.