I don't know why there are suddenly so many, but I do know that a large majority of them are a complete waste of time and money. Only use a car wash if they have filtered water -or- you have salt on your vehicle (i.e. driving on salted winter roads). Paying for anything else is a large waste of money, as your car will still look dirty when it dries. Yes, that under spray is the most important part of the wash if you are driving on salted roads. Don't skip it.