For most conventional satellites (and let's not forget second stages), the cost of deorbiting it if it fails is immense because it essentially requires launching a "tug" which didn't even exist until recently. Because it was so exepensive, people were allowed to ignore it. We'll probably eventually look back on this attitude the same way we view 1970s cars that didn't use known safety features.

SpaceX is being forced to innovate in this area because everybody realized the YOLO attitude towards space junk doesn't scale to thousands of satellites.