Pretty much the story of modern civilization. Just step outside and check the temperature, and look up at the clouds and guess if it's gonna rain later. Wear a sweat shirt or waterproof windbreaker if in doubt. Or you can just not care about getting mildly cold or wet. I say this as someone who spent 25 years in Minnesota.
But sure, you don't need umbrella either and we could all be driving open cars :)
Don't get one if you don't want to, the discussion is whether it's useful and it is. Not just for the weather not just for rain. For many little things in life.
That's one example. Schedules, playing music, guitar tuner, uke tuner, metric conversion when hands are dirty from cooking, and plenty of other examples are abundant in our house
Nothing complicated about it, it's just a reality for many people.
Not sure what you think you are proving here.
I didn't really think of rain in my original comment because when I was growing up we literally just walked in the rain.