I got laid off literally less than 20 minutes after I finished everything that needed to be done for that quarter. They told me they were waiting for me to finish, and that they had lied to my face about finding me a new position when they closed up my office.
So to expand on these, because a lot of people seem to think “it’s because they cared”, that’s only partially it.
Back before faster travel methods, if you wanted a small bird for any reason and it had to travel any significant distance, you would assume at least a 75% fatality rate from stress, with that increasing to roughly 90% over greater distances.
So canaries and finches were expensive, and unless your mine was close to a port city, you’d be traveling 3-4 days at least. Need 4 canaries? Better buy 40.