Need help understanding Allah's decree and fate

My mom has always said "its Allah's decree" whenever something goes wrong.

I'll give a few examples when she would say it.

- A reckless driver gets into a car accident and kills himself and another innocent person

- A negligent doctor who accidentally kills the patient by prescribing wrong medication or discharging them without further tests claiming they're ok.

- A plane crashes despite the pilot doing every single check and making sure everyone stays safe so this time it isnt the humans fault (everyone dies in the crash)

Please help me understand this. Do we just say this was all Allah's decree. I understand it is and their time was to leave at that specific time but lets say the car crash didnt happen would they still have died at that time because their time was written but due to recklessness they died? How does it work?

And the plane crash example, I would say this one was Allah's decree fully (I think) since everyone made sure to stay safe but it just had to happen. But the other examples the driver and doctor decided to be negligent.