If you'll allow me to nerd out a little. I love trains as much as the next guy. I also love arriving at the next station alive. Every single time. And i also want my grandchild to arrive at the station Alive. Every single time.
But by the time we start to actually lay down the tracks, a whole lot of work has already been done. Ground has to be sampled along the way. The ground has to be prepared, large boulders has to be cut/blown apart. Engineers and geologist must have had time to calculate that the ground will hold, perhaps certain areas needs to be reinforced more than others The ground has to be owned by an entity that can authorise the use of it.
Signal cables has to be drawn. There has to be space for trains to pass eachother. And then there are probably solutions to things we didn't even know was a problem.
What's my point? Of course trains take a lot longer than setting up a bunch of cameras on poles... I'd be more concerned if it was the opposite. And yes, I'm hillarious at parties.