Because 99% of those things apply to Jews.
And they can be found in the Mosaic Law which the Jews still follow to this day. So its the Jewish religious laws, which doesnt apply to Christians they believe there were abolished when Jesus died on the cross. Plus, in the U.S. there is a thing called seperation of Church and State.
Edit:
I didnt get it. I am against prop 8 and I agree 100%. I've been saying the whole time, it should be all or nothing. Dont take one thing and base it off the bible, but dont want to base everything else off the bible. Its not hurting anybody by letting gays get married. They spend over 80 MILLION DOLLARS to stop gay marriage! As though not letting them get married will stop them from being gay. THEY STILL GAY, its crazy. But thats the nature of some Christians, they think they have done a great thing by stopping this when in actuality they just blew alot of money on nothing, because eventually it will happen. Whether it be now or 50 years from now, eventually they will be allowed to get married. An d that will be 80 million dollars that could have feed the homeless and starving children (which is the real work of God) gone down the drain