The difference between wedding vendors and places of worship.

Which is more analogous to government recognizing marriage, a vendor or a place of worship?

I saw this news item in which a couple was denied use of a bed & breakfast for their civil union ceremony, the bed & breakfast only wants 'traditional weddings'.

Within my own church, it was made very clear the church was not a wedding vendor. We are a church. The photographer, the limo service, the florist, the reception hall, and a bed & breakfast are vendors. Vendors do NOT have a vested interest in your relationship, if it stays healthy or ends in a sad divorce.

Places of worship do have a vested interest, but why? What is in any religious belief system that values marriage? If there is a vested interest, is it something that could be defined as more objective without references to religion.

If government should recognizes marriage, in any form, then why? What is the vested interest for the community-at-large?

For instance, a government could repeal all marriage laws for everyone, would that be unconstitutional or would that be against all of our civil rights?