It's kind of the opposite - you get paid the standard for your position (with increases every year at a fixed amount) rather than being paid what you work to/can argue for. Technically a fairer system I suppose.
What's 'Single Status'? I come from a commercial environment and we all had to negotiate our own rates. So you could be sitting next to someone doing exactly the same role and being paid a hugely different salary, irrespective of age, experience, performance, gender or favouritism with the management.
Unfortunately that's pretty much how it seems to happen in many schools. You get dropped onto a pay scale, and gradually move up the scale over the years. Others probably have more details (and I may be completely wrong).
I left my first job because I got promoted to a point where no matter how hard I worked, I could not earn any more simply because I was lumped into a basket marked 'next promotion needs 10 years experience and you only got 3' (the irony was that I was doing a job needing 5 years experience) and yearly increments were fixed simply by virtue of turning up at the office each day.