I'm not saying that waterless/rinseless is the magic solution. I do feel that it is a viable option, especially in water restricted communities or for a quick/portable wash with essentially very little runoff.
Cost: approx 1 oz(ONR/DP) to 2 gallons of water. I bought a buy one/get one free of DP Rinseless (64oz total) for approx $16. This will give me 64 washes at that dilution(.25/per wash minus the water). However, I tend to DP/ONR as a QD(slightly stronger dilution) and find it to be a very effective window cleaner as well. So, now I have three uses for one product.
Now, the strictly waterless solutions would probably be a more expensive option for now than the rinseless and traditional washes. However, in a pinch, they work quite well and reduce runoff (again a sticking point for many detailers( potential fines) and others in water controlled communities)
Washing MF's in a washing machine is going to occur anyway, whether you do a traditional wash/rinseless/waterless wash. That waste water will be treated and the majority of that water will be reclaimed in many communities. \
Now I'm not an advocate for the abolition of traditional washes. In fact, many times it is exactly what is required for a neglected/heavily soiled vehicle. Rinseless/Waterless have their limitations. I do however like being able to wash my vehicle with a solution, sponge and 2-3 MF's in a 10 minute period with very little runoff.