Not for the fussy owner, but glass coating tends to be an easier way for the lazy owner to maintain the waxed look after each wash. Something like a coating over the waxed shine that last a lot longer than wax alone. More noticeable with older cars. My 07 E70 looked "almost" dull after each wash even though it was polished swee swee when i bought it used. My current 2010 car looks every bit shiny after each regular wash (even petrol kiosk regualar was), as it was coated in 2015, by the previous owner. Again it's not for fussy owner avoiding swirl and water marks, but for "lazy" owners wanting the car to shine after each wash. Did it for my brand new 2010 C200 and it's called Nano-coating in C&C. Was just as shiny standing next to it for all the 3 years I had it after each wash.