There was 25 Hz infrastructure in Ontario until the 1950s

https://www.lifebynumbers.ca/history/the-rise-and-fall-of-25...

Yep, the government had to go house-by-house, building-by-building replacing all electrically powered devices that could not be adapted. Thankfully it also happened early in the era of electronic devices.

it's substantially easier to run modern electronics off random frequency power than other stuff like an induction motor. A typical power supply is rated for 47 Hz- 63 Hz. But it'll happily run off almost anything higher than 10 hz and lower than 1000 hz.

universal motors in particular do not care at all about frequency

oh wow, 25 Hz was supplied to homes? I know New Orleans still has some pumps that run on some oddball frequency. It's part of the reason why they never work during the storms (when you need them). The "grid" is just a set of colocated generation sets

From the above link:

    Sir Adam Beck #1 ten 25 Hz generating units were converted 
    to 60 Hz or modified as follows:
    
    Units 9 and 10 to 60 Hz in 1956
    Unit 3 to 60 Hz in 1970
    Unit 4 to 60 Hz in 1984
    Unit 5 to 60 Hz in 1985
    Unit 8 to 60 Hz in 1990
    Unit 6 to 60 Hz in 1996
    Unit 7 to 60 Hz in 2009

2009! Talk about legacy support.

* https://en.wikipedia.org/wiki/Sir_Adam_Beck_Hydroelectric_Ge...

* https://www.opg.com/stories/opgs-sir-adam-beck-i-hydro-stati...