Why is a game about being a delivery boy so good? Is it the infrastructure building mechanic? Is it the batshit insane storyline? Is it the fact that every mountain is climbable? Is it the reserved use of combat and massive punishments for killing people?
Who knows, all I can say is I haven't had this much fun with a game in ages.
Yes. Once you get to South Knot, you need the highway so you can deliver materials and do timed missions. Ziplines are essential to deliver fragile materials quickly, bridges make robot deliveries more efficient, as you play and people in your game start forging paths, the game gets exponentially easier to the point that you're driving around delivering tons of materials at a time in your van.
When you get the BT umbilical knife, you can clear areas of BTs too and it's like you're slowly bringing the sunshine back.