If it costs more to replace degraded magnets or motors every million miles compared to brake pads, it will raise the cost of transportation. It's also not feasible to use in ICE vehicles - once you've filled your battery, the only place for that energy to go is heat.
It's not just a tradeoff between ICE and electric, or drum vs pad brakes, or rubber additive A vs B. It's a complex ecosystem upon which people's lives and livelihoods are dependent, with unpredictable and chaotic relationships.
The naive view is to simply replace the apparently "bad" material in tire dust, but if that raises the cost of transportation, food prices go up, quality of life goes down, nutrition suffers, and possible downstream effects end up causing more harm than good.
This isn't to say we shouldn't bother, just that a superficial approach targeted at a single issue could end up doing a lot of unintended damage, and there's no bounded scale of harm. Trying to reduce cancer rates by .0001% might end up reducing average lifespan by a decade, or some other consequence that's orders of magnitude more impactful than the thing being "fixed".
We live in a complex and dynamic system; the supply chain sits at the base of it all. We benefit from the economies of scale serving the supply chain, so we have access to cheap vehicles, efficient and cheap long haul trucks give us access to food and products. Tinker with that too aggressively and people can die.
The best route toward action on things like this are cultural - educate individuals and make alternatives available. People can adjust at their own convenience, and the trend of markets will resolve on a balance between health and safety risks and convenience.
You could simply ban private cars, and presumably 35k fewer deaths would occur each year in the US, and we could work on monolithic solutions to things like brake dust and tire dust. We've decided that our collective quality of life and the benefits conferred us by allowing private transportation far outweigh the harms. We need to find where the balance is between the potential harms of these dusts and how much we're willing to give up in mitigating those harms.
Anyway - it's not a trivial exercise, it's a microcosm of the global economy, with surprising complexity and dependencies at every level.
>We've decided that our collective quality of life and the benefits conferred us by allowing private transportation far outweigh the harms
Speak for yourself. At least in cities, cars and car-centric cities have absolutely destroyed our economies. People drive for trip less than a mile because walking is miserable, and walking is miserable because the city is built around driving and without regard for pedestrians needing to constantly cross major intersections.
To be fair, cars aren't the root problem here - the root problem is the hypertrophic cities craze that started in the 1780s that made streets so cavernous and muddy (with incredibly wide streets, the middle was often left unpaved to save money, since there was plenty of room on the side to walk) and miserable that cars were a genuine improvement.
