they were. But they used asbestos in a lot of things back in the day. I worked in a building with asbestos in the floor tiles. When they did constructions that involved removing the tiles, it became a big deal.

Asbestos isn't that harmful, until it goes airborne. My understanding from research (I worked expanding a landfill that took asbestos at one point). is that the particles are too small to be caught by our bodies defenses and when it ends up in your lungs its cancerous. Asbestos in brakes seems like a bad idea.

see: https://en.wikipedia.org/wiki/Mesothelioma