When they master the problem they get to erase the highlighter ink.

The BAZIC ones have like a magic ink based erasing mechanism while these are more friction based in that you actually erase the highlighting like you would erase pencil markings

They do not blur ink (except on a freshly printed document that used an ink-heavy text, but that was honestly not the fault of the highlighter), and they erase perfectly.

One problem...the ink has a ghost, especially the pink for some reason

They are dry, smear the ink and in general leave a lot to be desired.

The ink in these was messed up when I received

The problem with normal highlighters is twofold: even the best ones can blur ink on printed out documents (not as much books because the inking is of better quality; this is mainly an issue with articles or papers that you print out on a home printer), and secondly, you cannot erase the highlighting.

I have used other erasable highlighters before, but they used a clear ink that dissolved the color, and you couldn't mark over it again

but I've had a few pages that ended up with smeared ink

I hate them because they smear the ink on my printouts and make a black smudged mess.

Also, because the Frixion uses some kind of wet ink eraser, it was more likely to smudge the underlying highlighted ink than the Pilot.