I agree with most of these responses but will add some ideas of why some SS washes are dying.
Profit margins are low because expenses are high these days if you are a good operator. Most customers that use SS (other than the ones that can't use an auto because of size or other reasons) perceive it as being a low cost DIY wash. In reality it is not at the well run washes. For example it is nothing for someone with a truck to spend $12 to $18 at ours. Cars are about half to two thirds of that. That is at $2.00 for 3 1/2 minutes which is about average around here on the better SS washes. At that price you are into the price of an auto.
Auto wash equipment has gotten a lot better with less damage issues.
People are getting lazier and would rather wait in line for an auto so they can look at their phones.
Society's morals are getting worse about other peoples's property. Operators are less likely to fix items that are cosmetically damaged from abuse or vandalism but still work. The operator might think that if it is replaced it will happen again soon and the place may turn into a money pit. Customers may perceive the place as being run down or that it has turned into a bad part of town and start going to an auto wash.
Some people are somewhat scared to got to a SS wash these days (especially unattended washes) because of all of the bad things they see in the news that is happening out in society. They might feel safer staying in their cars and wait in line at an auto.
EEs are killing it when it comes to
marketing. For one thing they have to market big time to get enough people to come to them to overcome their high overhead. Not only are they telling everyone to "come here!" and "we will get it clean!" but also that they are a "3 minute car wash". Time is tight for some people so they are going to go to the car wash that they are told is the fastest and self serve is not what comes to mind. Who is
marketing their SS wash? (one that is SS only) Crickets......
Almost all EEs give away vacuums and SS charges for them.
Some people would rather go where there is an attendant in case there are issues. This only has to do with SS because most are unattended.
A lot of the older SS washes are built in the old part of town and the new EEs are usually in the new shiny part of town. People like shiny.
These are just some random thoughts that I have been harboring since being in the business for the last year and a half. Right now I'm thinking the SS market is here to stay but only if you can get the right combination to work in your specific area. I have other thoughts about it but don't have time to type it out and turn this into a book. Gotta go now.....vac hoses to pick up.....trash cans to empty....mud to hose down....