Generally it can work, my experience with Formula 4....
In Connecticut with mildly hard water not extreme like here -
It worked somewhat well. Two issues.
1. I had to really douse every inch of the car with it. Not a fast step in washing the car, it takes time remember we are talking directly spraying everywhere the grill, wheels, all lights along with all painted areas and windows and using alot of product not a quick pass over. And notice he never shows actually spraying the product on the whole car just a quick view of one area making it seem like a quick process. Just my own opinion, the car he used in the video was freshly waxed or had ceramic applied.
In the remarks on the video someone suggested using a cannon, and I think that would work much better and just like that person says you would use more product but probably a quicker process.
2. There was always some spots but I can say nowhere near as much. However where the water sits on plastic - especially the grill area even lights spots seem to still form, but can be removed much more easily. But you still do have to spend time removing some spots.
If I had to wash the car more often I would be inclined to get a cannon and try the product again. But with such hard water and having a couple of really good car washes right here where I live, a 10 to 15 minute time period including driving there to get a very good auto wash with no spots and very good wheel cleaning is more tempting.
I then put on the quick detailing wax and it looks great for good amount of time.