To humanity today, the Solar System is still overwhelmingly vast.
The information transmission links within the Solar System aren't just about lining up the eight planets and building a fiber-optic cable running through them. That's far from sufficient.
The planets in the Solar System orbit, each with its own cycle, and the distances between the closest and farthest points are vastly different. When two planets are at their most distant, there's even a sun and each of their orbital radii in between.
No signal station can bridge such distances.
With today's human capabilities, to transmit signals, space cities must be built around planetary orbits as relay stations.
This is also why Protector's control decreases significantly beyond Mars's orbit.
"Building infrastructure around Mars's orbit" and "building infrastructure around Jupiter's orbit" are not of the same difficulty.
