That article is a perfect example in proving the age old saying that "You can't believe everything you read". From it's perspective, it is implying that all hand washing is harmful to a car's finish, but doesn't take into account the many variables involved in the process. The point that it is trying to convey is that full service car washes are in fact better for your car's finish than hand washing, which simply isn't true.
Just like anything else we do in this world, there's a right way and wrong way of doing things. Hand washes are no different. Yes, if you don't use proper wash techniques, use sponges instead of high quality clean wash mitts, don't pre-rinse well, use dirty water, dry with dirty/abrasive towels, etc. etc., then you can do damage with hand washing. But, the article doesn't discuss these things only stating that full service washes are superior.
Just look at the people conducting their tests. One was using a brush and the other one was washing by the lake! The guy at the lake probably got all his water from there as well. In these types of situations, of course there's going to be damage induced. But, instead of educating readers on the proper methods of home hand washing, they hype up how "safe" it is to have a full service outfit wash your car, failing to mention all the dirt and grit caught up in those velvety soft tunnel wash cloths coming off of the hundred and thousands of cars going through and the cheap quality usually dirty towels used in the drying process. They even mention the low water pressure of garden hoses as a contributing factor. The pressure from my garden hose is more than adequate and i use my thumb to increase the pressure significantly for pre rinses and such, but have you ever seen any tunnel wash with a pre-rinse cycle? I surely haven't. All the ones I've seen simply throw soap on the car and scrub away. So, where's the benefits of the high pressure water there?
So, long story short... hand washing peformed by someone who has knowledge of the proper techniques, materials and has basic common sense regarding car care, is many times safer than your local full service car wash. Unfortunately, the vast majority of the hand washing population has neither of these attributes, which wrongly leads to beliefs such as that depicted in the article.
