Brian's (eurekaprice)'s answer covered it pretty wel
It's the surface available, mainly. And some living conditions.
Seen from here (Germany), large carpeted areas have never been a major concern.
After WW2 it was predominant to get rid of dust at all, so any good stick vac/ handheld /canister would do.
50s: Starting the vac business, most firms came up with stick vacs (resembling the broom), Vorwerk had a big influence on that (their tiny handheld didn't make a good appearance in shops, so they took to door-to-door sales)
60s and 70s: More and more fitted carpets were sold. Result: More and more firms came up with "Klopfsauger" (= beater type vacuums, this coming from Hoover's "it sweeps as it beats as it cleans") Still, Hoover was considered the "second choice" and "off the shelf" cheap brand (Vorwerk having introduced its extra power brush for any stick vac being sold)
80s and 90s: Dust allergies, fear of dustmites and all that: Retreat from fitted carpets, still no sufficient square metres (Europe IS and will remain cramped, so many people just kept their machines as they were bought in the first place). Besides: Some homes had fitted carpets now, but they would not lift up during suction, so the industry changed from "Klopfsauger" (beater type vac) to "Bürstsauger" (active brushing vacuum) and the beater bars were gone. Even our language reflects this: the term "Klopfsauger" is gone today.
Upcoming "laminated" (= wannabe wood) flat floors, some throw rugs here and there, still lots of furniture everywhere.
The trailblaze of the swiveling combo nozzle (sweeps around any chair leg, click and you are ready to go for carpets). Follow up in corners (Grooming and deep cleaning being one of the things "to be done some day, ok" = never)
2000s up till today: Europe still cramped and lesser surface than compared to the US, furniture taste swinging back to "minimalistic 60s revival" = flat and blank surfaces, more wood, less fabric = still no full chance of full textile surfaces, let alone fitted carpets all over.
Upcome of the "bagless" ingeniuities and cheapo-vacs (Mr. Dyson and DD zigzag filters). (No money for a PN for THAT price).
Overall: Each time a substantial PN came up, customers would complain about the extra costs for an electic hose or wand (helping them nothing or rarely). So companies took to offering PNs as an extra tool, cable clips included (in case you want to do this extra "to be done job" every once in a while)
ALL manufacturers here offer power nozzles, but all do this as an extra tool (on option), it is hardly ever sold directly (apart from Vorwerk, they do sell it as a standard, an extra motorized unit gives you extra points on your sales score, logically, it is door-to-door business, isn't it?)