I'm not a legalist like you, but it's still a sin to profane the Sabbath for anyone who can see how much it benefits them.The "why" is obvious. it is not a sin for non-Jews to not keep the sabbath. It is not sin for you.
More legalistic thinking. There is no real difference. You're just coming up with pointless labels.These are religious groups. I asked for tribes and nations.
We do see the term widely used all over the world though. Just because people lose sight of the origins of theses terms, it doesn't then follow that they never knew, or observed the Sabbath.If it is the default position, we should see the sabbath widely observed in a multitude of cultures over the earth, and we do NOT.
It's necessary for them just like it is for you.Sure. And they are doing something unecessary.
You make it sound like a chore. That's the real difference. For you it's work.There is nothing particularly wrong about taking a day off work -- I think it is a healthy thing actually. But it is not obligatory for non-Jews.