Mostly, I get the impression that the non-believers that say these things seem to think we're not aware our Holy Scripture says it. They think they've discovered something in a casual browsing that those of us who attend church week after week and study the Bible in context have somehow missed.
When you hear someone cite these laws or ANY OTHER biblical law that seems silly/no longer relevant/outdated/inconvenient/barbaric, realize that the best POSSIBLE intention for doing so is because they think they are protecting something valuable. In every instance, what they have placed in priority is either bad for them and they'd like to justify it - or it's good for them and they ignorantly THINK Christianity is against it, so they're trying to justify it. In either case, the idea is to find one biblical law that even a Christian doesn't think you have to follow and collapse the whole legal system with it.
It would be a whole lot easier and more honest to approach what you're REALLY having hang-ups about, and do a bit of research. The only thing that makes it difficult is that you're invested in one particular outcome.
So, now that we got THAT out of the way, why does the Bible even HAVE these verses?