Well, it's not easy to come first in 2 Unit.
It's a relatively easy maths, I agree with that. But coming first ain't easy. It requires luck too.
To come first in 2 unit, you need to get 100% basically. And no matter how good you are, there is still a chance that you can make a mistake and simply forget about that.
Imagine getting 119/120 or even slightly lower in 2 unit maths. That should serve you around top 5-10 spot in the state for 2 unit maths. But that's NOT 100/100 scaled mark. More like 98-99s. And if you consider that, you will only have 3 unit of maths.
Now, look at the other way. You have 4 unit maths. That's 4 UNITS OF MATHS. Only one unit more than 3 unit BUT....if you are someone who doesn't have any extension subject or 1 unit subject apart from maths, that can save you the stress of going through another subject to make up for that 1 lost unit by not doing 4 unit.
And I am telling you, 4 unit scales awesome. In 4 unit maths, you can still make mistakes. But it's differnet to 2 unit maths. Losing one mark in 2 unit will cost you heaps generally. But it's little bit different for 4 unit. Since the gap between individual is SO significant that 1 mark hardly makes difference.
In terms of safety issue, IF YOU ARE GOOD AT MATHS, DO 4 unit maths. Don't take to run a risk of doing 2 unit maths SO THAT YOU CAN COME FIRST IN THE STATE.
If you don't come first or top 20 in the state, scaled mark is generally quite shit.
This year, 100 = 100 scaled but, 99 = 95-97 scaled and 98 = 94, you can picture it right?
compared with 4 unit maths, 90 = 91-92, 91 = 92-93 or whatever.