Automatic typography isn't! Let's suppose for example, there is $P_A$ in the text. According to the rules of math typesetting if A stays for description like "Alice", it should be set in the current math roman font i.e. $P_\text{A}$. So $P_A$ looks suspicious, what shall the typesetter do? 1. ignore everything and this way leave the typographic responsibility to the author; 2. set it correctly, because she is one of those underpaid TeX-typesetter, who can read out of the text, what A stands for; 3. send back a question to the author for clarifying. And this is just a simple example. The before/after gap betweeen author typoscripts an proper typesetted books is enormous.

Sadly, the job of the scientific typesetter is not valued this days any more.