I feel the same. The Golden Gate Bridge took 3 years to build, start to finish. It was the biggest suspension to have ever been built at the time. Compare that to any modern public works project of today. There are countless examples of how we used to be able to build things before 1970.
11 people died during the construction of the Golden Gate Bridge. We have onerous safety requirements and red tape which is why everything is so slow. Very few people die on construction sites now. Do we want 11 dead people or do we want things done extremely slow? I guess as a society we have answered that question.
Per Wikipedia, the Golden Gate Bridge was proposed in 1917, approved by the state for design in 1923, funded in 1930, started construction in 1933, and completed in 1937.
The reason modern projects take so long is that so many of them are stuck in design or awaiting funding stage for what feels like interminable ages; once the construction phase starts, they tend to go fairly quickly. But if you look at projects 100 years ago, well, they also seem to have fairly lengthy pre-construction timelines. It's just that we conveniently forget about those when we look back on them nowadays.