Ah, my context is different, I live/work in Sweden where "same-day" firings are completely illegal.

Job safety is insanely strong here, if you pass probation it's extremely unlikely you can be fired. Even if your job is not required anymore there is a "first-in-last-out" policy which would mean anyone hired after you would have to go first.

So there is huge financial incentive to ensure you only hire the right people.