Hi D- if you don't use the 1.5 fret, then you'd not likely use its 'mate' that's one octave higher (the 8.5 fret).
The reason we don't often see such extra frets mentioned in tab is this- the reason for adding them is to enable you to play in a different mode and key without re-tuning. 90% of tabs seem to be written for DAd or DAA tuning... both of which can be played without using the 1.5 or 8.5 frets. Bluesy tunes might use them more often though.
I find the 1.5 and 8.5 frets are handy for me when playing in fiddle tune sessions. One example of where I find it useful is if fiddlers switch to a modal-y sounding tune in the same key and then switch back to a major-y sounding tune in the same key, without much of a pause. Since I don't use capos either, those two extra frets give me more options in weird fiddle session situations. But for folks who play typical pop and/or traditional folk tunes mostly from tab, they might rarely run into instances that call for a 1.5/8.5 fret.
Those irritated by grain of sand best avoid beach.
-Strumelia proverb c.1990