Well, if you crunch the numbers, you get the following:
Originally Posted by holmburgers
2000 lp/in = 78.74 lp/mm = 6.35 um (micron) line or space
2400 lp/in = 94.48 lp/mm = 5.29 um line or space
2750 lp/in = 108.3 lp/mm = 4.61 um line or space
Looking at those numbers, they are about 10x the wavelength of what might be considered red, green and blue light, respectively (though the blue seems a little long to me). I would guess it has something to do with the power of the viewing lens and the angular offset that is desired/needed. I would further guess that other combinations of viewing angles and lenses might benefit from different line screens.
I'm very definitely not an optics person, so maybe someone else can explain further, 'cause I'm at my limits, here.
BTW--First link in post #14 requires membership.