No, but is the same as not letting them walk 2 miles on their own
No, it’s not. There are segregated car-free walking lanes along most roads, and teaching pedestrian safety is straightforward. Cycling in heavy traffic is far more dangerous for a kid. We don’t all live in bucolic wilderness – by definition.
The roads were sill busy in the 70;s and 80’s
They weren’t anywhere near as busy, and there were far fewer stupidly positioned housing estates with hardly any roads in and out. Where we live there are two roads in and out, one is a windy lane with about 100x more traffic than it should have, and the other is dead busy. The 60s/70s estate further in has loads of access points and off-road paths all over it for traffic free access.