They were probably too expensive, or not sufficiently reliable.
> With the spread of electricity and affordable alarm clocks, however, knocking up had died out in most places by the 1940s and 1950s.
> Yet it still continued in some pockets of industrial England until the early 1970s, immortalised in songs by the likes of folk singer-song writer Mike Canavan.
I was trying to find the Simpsons clip where Lisa borrows the Native American technique for pre-dawn ambush: drink so much water that your bladder wakes you up early!
The article said they usually had inverted sleep schedules and they woke people who had odd or irregular shifts. Staying up all night was probably the best option for the work
> With the spread of electricity and affordable alarm clocks, however, knocking up had died out in most places by the 1940s and 1950s.
> Yet it still continued in some pockets of industrial England until the early 1970s, immortalised in songs by the likes of folk singer-song writer Mike Canavan.
The reason for that isn't clear.