After my experience of working with a US carpet cleaner in a rental villa my guess would be that the carpet in the picture is actually white or an off cream colour ad its getting rinsed through at the end of each let.
My Dad trialled some Hydrox when we first picked up the samples and everywhere he spot cleaned stood out a mile from the areas being done by the guy resposible for the area we were in.
His method, for those that dont know the story, Hyrdoforce sprayer with Clorox bleach, spray down heavy and rinse with TM & Fresh water dumped straight onto the drive.
When I questioned it he gave me a big thumbs up and in his best Mexican/English said "Is Olefin - Is Okay"
I left with my eyes on fire and my skin back to the translucent white it was when I arrived a couple of weeks earlier.