I think the attitude about crossing the border as no big deal can be tied back to our changing attitudes about marriage. In the past fifty-sixty or so years, the shift to "it's only a piece of paper, etc. etc." mirrors the position that citizenship is no big deal, it's all the same. living together may look like marriage, but it's not. Likewise, being here in the country working raising kids etc.. etc. may LOOK like citizenship, but it's not. Both issues show more concern for feelings and appearances than following the law and commitment.