In Edmonton, it was moreso because the city was too broke during the Great Depression to invest almost anything more than light maintenance - like replacing old rails and streetcars. In 1937, city admin recommended switching completely to trolley (and some gas) buses rather than trying to tackle what was then a huge infrastructure deficit, and a 1938 consultant report agreed. World War 2 paradoxically bought the streetcars some more time, since bus deliveries almost completely halted during the war, while also putting more strain on the system than it could handle. Foster Palmer, a Harvard librarian who
shot colour footage of Edmonton's streetcar network, among others, in 1949/50, noted that Edmonton was actually a rare exception among North American cities:
"Edmonton provides an interesting contrast to cities which will not spend a penny on new street-car facilities after a decision for eventual abandonment has been made. The management here is trying very hard to provide good service in a rapidly growing community. Service on Route 1 is excellent in frequency (3 to 5 minutes), but rather slow. The Calder line has ten minute service during most of the day, which is very good considering its outlying location. All trolley fans who can still possibly do so should visit Edmonton while the cars still run. The High Level Bridge is one of the true “greats” in street railroading."
And indeed, Edmonton continued to invest into new rails up until 1946, as well as rebuilding a burned streetcar due to wartime demand, testing new brake shoes and stop/go tail lights, etc. They did the best with what few resources they had.
Lastly, ERR/ETS administration did not close the door completely on retaining streetcar service, even as late as 1949.
"Mr. Thomas Ferrier, Manager of the Edmonton Street Railway, takes the position that Edmonton, even though it has grown extremely rapidly and now has an estimated population of close to 150,000, is not large enough to warrant the cost of a street-railway fixed plant in its transit system. He did, however, say that the North Edmonton line* would be retained for a few years, and, if they felt that Edmonton had continued to grow rapidly enough in the meantime, the line might be retained permanently and modernized. [...] Condition of track was an important factor in bringing about Trolley Coach conversion of most of the system. Mr. Ferrier said that if there had been good track throughout any one route, PCC’s would have been purchased. But North Edmonton was the only well-railed line."
Even in the dawn of the automobile era, Edmontonians remained avid transit riders. According to a
ridership report in the
ERRS Archive (Edmonton is RBT-21), the transit system served 47,995,000 riders in 1949-50 - including more than 10,000,000 on just the one remaining streetcar route by that point. That works out to around 330 transit rides per Edmontonian. In contrast, ETS served 87,646,600 riders last year, which works out to around 73 rides per Edmontonian (compare that to the roughly 69 rides per resident on that one streetcar route).
*The 'North Edmonton Line', by that time, was simply the part of the main streetcar line that was north of 97 Ave. Palmer said of it: "[...] "the last best hope” of the system, this is the heaviest route. Its track was relaid in the late 1920’s at a cost of $185,000 per mile, and is in superb condition today." At the time, residents had recently voted yes in a referendum to convert the streetcar deck of the HLB to four vehicle lanes. After delays and cost increases, it went to a second plebicite, where there was a majority in favour but this time not the 2/3rds necessary, so the project was cancelled. That's why the "North Edmonton Line" was not the only part of the system to remain in service until 1951.
You can learn more in
this Wikipedia article I wrote, or the sources I cited in it—which are even better.