Out of my four subjects, Law and Religious Education (Philosophy and Ethics) are the two subjects that I understand a lot easier, compared to my Politics and History. I've seen that Law and Politics come up quite frequently on the "black lists" or the "least respected" lists, and the other two don't. I guess it does all depend on the person who is studying the subjects, but when people say Politics is easy, it might just me who doesn't fully get it, but I feel like face-palming myself every time I enter the classroom, and History for that matter.
I don't think you can really say which subject is the easiest, because people who actually take said-subject may completely disagree because it all comes down to the person and what they enjoy... I, for instance, wouldn't go to my friend, who is currently doing art, and tell them "Oh, Art? That's so easy, you should try doing one of my subjects blahblahblah" because I know that art can be hard, even though it may seem like an easy A-Level. Same goes for every other "easy" A-Level out there. I don't think you can compare Maths to History, because they take different skills etc.
... In the end, I'm not really saying that there are certain subjects which *ARE* easy, and that while SOME may be least-respected, they can still take you far. Like, I saw someone post how Law is least respected, and someone replied with a comment about solicitors. It is true - how do you expect solicitors to gain knowledge and become well-respected in their field of work if Law is seen as easy and least respected? :/
Also, not posting this for people to go on, it's just my view that not all a-levels are that easy and require work, some maybe more than others.