Your experience might work in a closely spaced situation (hence your odd comparison of moving at a magnitude difference velocity), where most people pick the same mall and live close to eachother, but that's not how large countries work.
Not to mention, try carrying the things I put in my 5700lb car (without any planning) on your bike.
I made the math easy, but it's the same arg if it's 45. The only legit arg I can come up for your point is sometimes I want to run or ride a bike, but in that case, I'm going to avoid roads even if it's 100% 3 cylinders Geo's, or just follow my routine and exercise at the gym since it's more fun than running alone to xyz when I really just need to get something done.
Also it should be mentioned that your driving makes the city less pleasant and more dangerous to walk or cycle in, encouraging others to drive, in an unfortunate feedback loop.