Because nobody knows about these, a "developed" country won't "humble" itself with buying things designed for underdeveloped regions, cities are designed around cars, car manufacturing is still a major backbone to most western industries and politics won't risk jobs by providing alternatives, it's "unamerican", leftist propaganda and queer, etc. In short politics is not rational, because humans are not rational. And that is neither good nor bad, it's how humans work. To sell them these ideas you must make people excited for these changes and we are pretty fucking far from getting people excited about changing for a better, greener society.

Edit: autocorrect thinks I'm short

I don't think that's a terrible idea but the buffalo bike is way overbuilt to be essentially maintenance free. IIRC, it even has thicker tubing than needed just to make it easier to weld things to it. This makes it great for poor, rural, developing countries. But its like 50 pounds. I'd rather have gears and the ability to carry it around at the expense of occasional maintenance. In America, it's easier to find parts, tools, and bike shops to keep a bike running.

You can already buy bicycles that cheap. Maybe not quite as rugged, but perfectly workable. But I suspect that most people in North America wouldn't use them even if given free for various reasons (that include urban sprawl and bad weather).