Seatbelts were available in the mid 50s, it took until 1966 for Congress to mandate them.
point being, mandating backup cameras is an overreach of safety regulation, but not for seat belts.
[1] https://www.kidsandcars.org/2018/05/14/after-his-sons-tragic...
we don't regulate for the people (US, annually) who accidentally drown in a bathtub (~300) and get injured in a bathroom (~250k), even though it would address more harms (at a larger scale and possibly greater cost, depending on the mitigations).