I would think because its normally hydrophobic glass where
you have spotting issues and hydrophillic glass the water tends
to sit on the glass like a sheet and when drying tends to evenly
shrinking down or inwards and gives you less chance of spotting.
If they had truly developed a product that makes glass behave
in a hydrophillic way that would be of great interest to me personally
unfortunately i dont think this is the case.
Let's not forget the main aim is to take dirt OFF glass. Hydrophobic means the water will shoot off the surface, taking all of the dirt with it. I don't, and nor do my lads, have any issues with spotting in any glass, whether it appears to be hydrophobic/philic. I think that comes down to technique and water quality, not the properties of the glass itself.
Therefore, a hydrophobic product is more desirable, taking the dirt away as fast as possible. Hydrophilic will encourage the water to stick, keeping the dirt on the glass.
It will be interesting to hear the opinion of others about my previous post...
personally I find hydrophilic glass dries quicker and lets not forget weather
conditions have an effect on what condition the glass dries especially this time of year
when we get a lot of wet and especially windy weather.
I clean a lot of windows on busy roads where you get more than a bit of wind
and is made worse on windy days I have little problem with hydrophilic glass
which dries quickly and I guarantee(and this happened when I used 000ppm)
that with windy conditions blowing, hydrophobic glass where the droplets of water
hang around longer especially this time of year spot I put this down to dirt
in the air attaching itself to the water droplets so I have always bladed this glass
dry.
I like to work in as many conditions as possible so hydrophilic glass is more
preferable to me.