Most people can't look into the abyss, with out trying to find his or her reflection.

I think if it's just different tastes then it's silly to quibble. Major differences in views might get in the way of long-term relationships. In general though if two people like each other and are otherwise alone and lonely they should just enjoy each other's company. For most folks being lonely sucks so maybe taking a chance is worth it. Just be sure there are parameters and don't give in to an aggressive person who just wants to dominate. Two people who get along though, go for it. It may not last, or it might, but you still shared with someone and can be happy for that.

Yeah, the problem is I'm having an argument about who has the best cheese fries and instead of insisting I'm correct, I end up caressing and having sex with a complete stranger on the bus. He insisted he was hetero, but what the heck.

Sounds like you are feeling defeated. It can be hard to connect with others and share intimacy. Sometimes it helps to take a step back and look at the dynamics in your relationship. So much of communication is symbolic and often filtered through our insecurities. I'm sorry you are having such a rough time. Sending you peaceful thoughts.

Trying to prove that you're right is a power struggle I don't want to get into. If I don't agree with someone, I just want to understand where they're coming from.

If it were me being asked I would have to say " Every one is different to a certain degree. I guess one would have to prioritize ones values and learn to live with the rest. In essence, don't sweat the small stuff."
If you know and love your partner you will learn the mystic art of shutting up. More can be said without uttering a word.

Because we are humans and have individual ideas about the world and our fellow man !