Glasgow has had a very interesting history of street/area lighting, with a lot of early electric installations being bolted to the tramline poles, hence all the overhead wiring.
A true gem and relic of the past may still remain on an old overgrown path off Maxwell Road, with these fantastic wartime style "upside down dustbin lid" incandescent lanterns, you can just see one in this google street view:
https://www.google.com/maps/@55.8431407 ... 312!8i6656I don't know much about incandescent street lighting so I'm not sure whether they'd have been say 300W lamps or the special series type ...
Looking at the a more recent capture of this GSV, it looks like the lantern itself has either dropped off / been removed (from around 2015).
The prewar lanterns and equipment found in the city, were produced by Credenda Conduits Ltd of Birmingham. These were to the design and specifications of the Glasgow Corporation's Lighting department (under the auspices of Messrs Ward & Mann). They lasted for a surprising amount of time, before the huge influx of SO/H lanterns in the 1950 / 60s replaced them (although it is apparent that small pockets of GLS lanterns survived until recent times, albeit long out of use).
One such product was introduced in 1937 which was designed to 'clip inside' the numerous RLM type reflectors found in the city. I think this would be the 'dustbin type' GLS lanterns to which you refer.
Turning to the surviving installations in the area, the widespread use of the overhead feeds, was born out of the need to provide streetlighting that was economical to both install and maintain (especially important when the expansion of the 1930s housing estates was in full swing).
The electricity / tramway undertakings were all part of the mighty Glasgow Corporation, therefore by avoiding the need to dig up the pavements to lay / repair cables, great savings would be afforded to the benefit of the ratepayer. Overhead cables were also easily accessible to maintain and repair. Only areas of civic importance were spared the visual intrusion.
The general public were long accustomed to the geometric 'web' of overhead cables as used by the tram and trolleybus routes, therefore the use of overhead cables on residential streets, would have aroused little opposition at the time.
Even in modern times, Glasgow has managed to keep much of its postwar lighting installations in service, as a result of a long standing 'make do and mend' policy.
The use of the same overhead cables system to supply the old tubular steel / concrete columns (and their galv' steel replacements in more recent times), illustrates how economical the Glasgow policy has turned out to be.
As to how long this will continue to be the case, will depend on the future expansion / redevelopment of the city and its surrounding districts.
Despite the reintroduction of trams in numerous UK cities, the imposition of what can be jarringly functional OHLE is less likely to be tolerated these days, especially in residential areas.