>This only started to change in the 70s and 80s
Which was my entire point. City wide infrastructure rehauls were massively easier and cheaper back then than today. The amount of nimbyism and red tape has ballooned exponentially in that time span, let alone the cost. Even NL wouldn't be able to do that today if they wanted to had it not done that in the 70s.
It's a big stretch to say that the 70s and 80s was "from the start", when the preceding 30-40 years had seen increasingly car-friendly infrastructure policy and development.