I've just never seen any numbers that close. I confess I know nothing about digital testers--or, more importantly, how to calibrate them.

With drop testing, unless you have extreme red/green color blindness--and people do, other than pH testing, the color changes are rather drastic:
FC and CC go from pink to perfectly clear with FAS-DPD.
T/A changes from bright green to bright red
CH changes from red to blue
CYA/Stabilizer has no color change at all, just a measure of how cloudy or clear the water is.

Only ph (and if you do OTO chlorine testing) require perception of color gradations.

We don't recommend strip testing. I have unusually good color perception, especially for a male (annoys the heck out of my better half! ) and yet I find the "guess" strips hard to read. They told me just today my CYA level was about 40 when in fact it was 60. (I use them for rough'n'ready quick testing to see if my chlorine is 'way low or my pH is 'way out of wack--either requires proper drop testing).