Sorry for the delay. I now have time . So...
Elementary Survey Arthur Higgins Lovat 1947 (PDF Library) | PDF | Surveying | Trigonometry
If you scroll down to page 5 which is the introduction you will find a short description detailing the difference between Geodetical and Plane Survey.
It is stated that in geodesy the earth is considered a sphere. That's an honest statement - it does not say the earth is a sphere.
Also stated is the fact that only surveys over 100sq.mls area are considered as geodetic survey i.e. spherical trig is applied to plane survey results to enable these to be mapped onto a globe , the inference being that there is no curvature found that cannot be accounted for within the limits of observational error.
It seems that 80 feet or so of expected curvature over a circle of diameter 10 miles is absent.
My own copy of that book is an earlier edition - but states the same.
That arbitrary (to me) limit still applies as in this 2020 exam paper
[Solved] The curvature of the earth is taken into consideration if th
Even wiki gives a mention - scroll down to the section " Plane v Geodetic Survey"
Surveying - Wikipedia
That page was last edited 4th October this year. When I first looked at this years ago I recall that the limit for plane survey was given as 100sq.km . Maybe I'm mistaken but at least it's in there now .
I've also read through a reprint of "Zetetic Astronomy" by Rowbotham .He writes in there that the during the building of Britains' canal and rail networks the government had to instruct it's civil engineers not to apply any curvature calcs to their designs and just use horizontal datum lines .
I will hopefully check that out if possible at some point , but the detail is a bit lacking.
Hopefully I've been able to clarify that a bit without too much rambling.