Of course she thought it was silly too, but yeah, we cycle everywhere and I've fixed a lot of flats now.
In their defense, I only figured out why you should bring kit everywhere because I've been stranded badly, totally unprepared. I was finishing a 400km ride, around 40km to go at 1am, and my tire went. It was cold, raining, low/no traffic, no cell service for most of the trek back, etc. I got home as the sun was rising, haha.
Here's more info if you're curious, it's a fun sport called randonneuring: https://en.wikipedia.org/wiki/Randonneuring
Here's an example 400km route from an area near me run by the BC Randonneurs: https://ridewithgps.com/routes/33536016
It's a great way to get to know areas better. Very meditative, challenging, and rewarding.
She's an intelligent person, accomplished in her own scientific career and a stimulating person to talk to, all great signals about her brain, but dumb driving sense pervades all intellectual capacities I think. I sincerely worry she will die in a car accident. She is positive it would be me, though - she thinks I'm "overthinking" driving and driving safety, which introduces far more danger.
I've been in two car accidents. Maybe that helps. In one case my friend backed us up into a street light really fast because he seemingly didn't realize the accelerator was the brake. The other time I was crawling down a steep driveway in bad weather and my car slid off the driveway, down a hill, and ended up in the ditch below. It looked like a severe accident at a glance, haha. It was actually very slow and boring as it happened.
At any rate, these events instilled in me that small errors can have large consequences. The feeling of your car not doing what you want it to, then being in a situation out of your control, really sucks. I'm not interested in the slightest in finding out how badly that can go. Whether it's because I left my seat belt off, I had a beer, I couldn't see out of my rear window properly, I got stranded in the cold - these are all enormously bad reasons to get hurt or die.
A lot of people have never faced consequences or witnessed the disproportionate result of minor errors, so perhaps driving is one of those things were (unfortunately) many of us learn the hard way, often bringing innocent bystanders with us.