The machines you mention are not truly "detailing machines" they are simply machines to apply chemical.
Yes, you can do an express wax with either machine concept, but if you want to make real money at express detailing you need to offer the express wax; express carpet shampoo; express seat shamoo and maybe even a super interior clean or interior clean.
Keep in mind, however, that express detailing feeds off of the car wash volume and self service washes, even with an in bay automatic do not have the same large volume a conveyor wash offers. That means you will not have as many customers to draw to the express services.
Keep in mind the express customer is your car wash customer, not a person off the street. The person off the street sees "detailing" and thinks you offer the whole package, which you do not with express. You can only offer this to customers with cars that are newer or in good condition. You are doing maintenance, not restoration.
I do not know of any self service operations that do a huge express detail business. Not to say there are not some, I am just not aware of any.
Regards
Bud Abraham