As a photographer I am able to get almost perfect single strand, single pixel, resolution of hair edges with Fluid Mask ($179) BUT....I have to shoot the model with the purpose of precise extraction in mind first.
Using Fluid Mask to extract...it needs...a mid tone, evenly lit, gray background...not chroma blue of green because the extreme color saturation of those two colors contaminates the hair from behind. The light gray shade works beautifully. Keep the evenly lit gray background about -1 to +1 F stop within the key light exposure so the light does not blow by the hair and loose edge detail. Do NOT use a hairlight so that hair is both lighter and darker than the background in the same area...add highlights in later. Keep the model 6 feet in front of the background so no shadows fall in the hair area. Put no complex background in the hair area...or he software will have almost a hard a time as seeing individual strands as our own eyes do.
With the above... I am able to get almost perfect hair fine extractions...but violate any step above...and you will be pulling your own hair out!!
The above image has too many areas where there is too little definition to give a great cutout with Fluid Mask.