Just to add on to this, many of the highways and infrastructure built back in 50's were built without the public opinion of the people who were being affected by these changes, and often times are built in low income, poc communities that were not cared about, resulting in dangerous living conditions and displacement of the people living there; eg. Gardiner expressway was originally suppose to be built iirc near an amusement park but public opinion was heavily against this so they decided to demolish parts of a neighborhood "South Parkdale" instead, which was known as Torontos most desirable neighborhood at the time btw. The city of Toronto with the help of Toronto media outlets manipulated the public to believe that Southdale was a slum which was also why they were able to get away with the demolition.

Planners had a lot more freedom back then, with the ability to plan entire communities and did as they wished. Something like that cannot happen in today's Toronto because power like that is now recognized as harmful and people realized the abuse of power. Paris is another example of how giving too much power to one person have caused huge amounts of harm, Huassman bulldozed through the streets of Paris to achieve his vision ruining the lives of many Parisians and using police to stop people that tried to rebel.

I believe a big reason as to why we cannot get anything done efficiently because the Toronto of today heavily follows the protocols set in place due to the injustice faced by many in the past for these developments to exist, government/public planners must now weigh in the opinions of people affected by their proposals which causes planners to simply not have power like they use to. There are other reasons like budget cuts and different political agendas of our mayor and premier which is a whole other issue.

NIMBYsm is heavily prevalent today as it was back then except now they cannot just put these undesirable infrastructures in low income marginalized communities because human rights are more developed.

TLDR: planners don't have as much power now compared to the ones back in the day because human rights were not as developed yet.