It isn't. I got 50-60% in Junior, now I get no lower than 85% in higher level LC. Apply yourself to understand the material of each topic and how they can link in with one another. Maths all links up and each topic mostly isn't an individual topic. It'd be bad to see it this way as it really is just previous knowledge but being built upon. Statistics, complex numbers, probability and calculus are new though. Aside from that its just building upon your foundation. To summarise, try think about how each topic links and how you can apply that. It makes maths much easier and more enjoyable!
You should just see Applied Maths if you think the exam questions in Maths are difficult!
Nah, in fairness, it could be that you're studying it incorrectly. Practising questions is vital since while an understanding is important, I feel that most questions don't really test it (unlike Applied Maths) so I feel that you can get by with a H3, maybe even a H2 just bruteforcing your way through problems and bullsh***ing your way through the rest (it works a lot of the time!). If you're really just having problems understanding the fundamentals of the subject (addition, subtraction, algebra and the like, relationships and all that) then you can't really bullsh*** I'm afraid so get help ASAP if that's the problem. Just spend time learning the basics/fundamentals, you've no idea how helpful it is to know them (and how to abuse your calculator and log tables, part of the bullsh***ing factor I was talking about earlier).
EpicArtifex, Yeah, that's annoying. You used to get a choice apparently. But remember that HL Maths has 25 bonus points going for it, Chemistry and Physics don't. For 25 bonus points, it's well worth it imo. It's by no means easy, but it's not at all more difficult than other subjects, at least in my opinion.