"It's raining"
This is Britain and it rains, and I'm not going to pretend otherwise. But the objection does more work than the weather does, and I'd like to separate them.
Look at the list from chapter 1 and mark the trips where it was actually raining when you set out. Not grey, not threatening, not cold. Raining. In my experience of asking people to do this, the count is smaller than they'd have guessed, and smaller still if you subtract the days when it was drizzling and a coat would have done. Most of the weather that keeps people in the car is weather you'd walk through happily if you were already outside. It only looks bad through the window.
Rain also has a shape, like most weather, and a ten-minute walk usually fits inside a gap in it. If it's raining hard when you'd have set out, wait fifteen minutes and look again. More often than not it's eased. The car doesn't teach you that, because in the car the rain is something you drive through and never watch.
The coat is the answer to most of it. A coat with a hood on the peg by the door, and shoes that don't mind a puddle, and the errand walk goes ahead in anything short of a downpour. In a downpour, take the car and say so. That's a reason you'd say out loud, and the rule allows it.
The dark is a different objection and it's a real one for some routes. When the Department for Transport asked people in 2023 what would encourage them to walk more, half said nothing would, and I'll come back to that half in chapter 15. Of the rest, the top answers were safer roads, meaning slower traffic and more considerate driving, and well-maintained pavements, meaning even, clean and lit. Those are answers about routes, not about weather. If the way to the shop is a lane with no pavement and no lights, that's not a default. That's a route that isn't safe on foot after dark, and chapter 22 is about what to do with it.
The cold, I'd only say, is what a coat is for, and that a person walking briskly is warm within five minutes in any British winter. The car, by contrast, is cold for the first five minutes of a short trip and has only just warmed up by the time you arrive.