> These are small companies not looking to scale
I actually disagree that the only reason why a business would need engineering like this is to scale.
That is a reason, and if that's the reason, these businesses will not need it.
However, there are plenty of other reasons. Automation and engineering of various business processes exposes issues throughout your structure, can safe hundreds of man-hours, and can produce better product than people can.
Much of my business is automating the generation of various reports. It may only save the business 10-20 hours a month, but you know these reports are solid (if the data is input correctly).
It takes the focus OFF the reporting and puts it ONTO the data: where it should be.
That's worth the 10-20k per app 10 times over.