Just sharing my experience, not the absolute correct answer. Others might feel different.
Idk about other country but some stringer here are nothing more just a job. A hired employee, get short time training how to use the tool, & did the job not knowing much about badminton. & Most often this kind of stringer just did 2 knot & their job never satisfy my preference. Tho some people i know say 2 knot are for lazy stringer but i didnt say it here cos im not stringer. Lazy or not, i dont much care but 2 knot job so far never please me.
While other hand stringer i like mostly use 4 knot & i dont need to ask for the knot. It will be 4 knot with the tension i ask & if i talk with them, most likely they also play which makes them more or less know or respect what they are doing.
This exactly like what u said.