So, I have a book here, which has an example for context sensitive grammar, and the grammar is the famous $0^n1^n2^n$ , and it has:
$$ \begin{align} S &\rightarrow 0BS2 \mid 012 \\ B0 &\rightarrow 0B \\ B1 &\rightarrow 11 \\ \end{align} $$
I agree that the above works, but what is wrong with just saying: $S\rightarrow 0S12 |\epsilon$
The above also generators the same number of $0$s as $1$s and $2$s.