Laws to protect the married

I've read that there are over 1100 laws that concern married people--although I've yet to meet a married couple who got married for health benefits or power of attorney or the tax benefits. If these laws are such great reasons to marry why don't men and women living together or confirmed bachelors think they are such great benefits, outweighing all other (like cost of divorce), and why not let parents marry their children, sisters and brothers marry, landlord and renter, etc. because think of the benefits--wouldn't need to hire lawyers to set up all those messy contracts for your estate, loans and mortgages, pension and health.

Polygamists are also waiting in line for society to recognize them--and to get all those benefits. It's probably cheaper for men than serial divorces. Homosexuals are about 3% of the population and transgendered and those thinking about it less than 1%. Although the ones who marry make the evening news, especially if they sue people who make cakes and rent their property for weddings, most are choosing to be free of those laws and keep their own wealth, pensions, homes, etc. just like many men who have fiancés, but not wives.