That's basically the point. At GCSE / Standard Grade / National 5 level, it's all about taking a basic and widely known argument, analysing two sides to the discussion with recognition of the positives and negatives, and then structuring it in a way in which to convey it in a manner where the correct and applied use of basic language techniques, spelling, and grammar, is maximised.
Only when you get to A level or whatever the English equivilant to Scottish Higher / Advance Higher is, do you gradually start to break down the complexities of the arguments in terms of what the structure of the railway is, what each concept (privatisation and nationalisation) actually means, and how it will affect diferent areas of the rail industry differently. Right now, it's about nailing the basics both litrary and factually.
For a school student as opposed to a uni student, it's about conveying the quality of your writing in accordance with the expectations with the course, not depth - and the OP's level, regardless whether the subject is English or Modern Studies etc, the suggestion I've given is perfectly suitable for it.
