On production guitars, the standard for a factory setup is often “good enough is good enough”. Here's an example...
Take a look at this (potentially) nice little Double-O:
Using a radius block, I filed the frets to this model's correct 12” fretboard radius. From the filings you can see that frets 3 through 5 were particularly high in the middle, whereas frets 9 and above were high on the edges.
When a guitar company doesn't do the required fretwork, the result is a guitar that simply can't play as well as it should. This manufacturer's solution to this is to set the saddle so high that the strings will clear all of these irregularities. Of course, the action is uncomfortably high, but at least it doesn't buzz.
After filing, this guitar's frets were crowned and then polished. This “post factory” fretwork allowed me to lower the saddle considerably and now this guitar plays far more easily and with improved intonation.
Yeah, it's a $300 guitar and sometimes I think I'm nuts. But I just couldn't let it go out the door knowing that it could be so much better.