"If Bob drove 60 miles at 60 mph to see Alice, he would see her in 60 min. If he asked her to leave at the same time and drive to meet him, he would see her in 30 min. No one exceeded the speed limit, they only drove half the distance simultaneously.]"
But the relative velocity would be 120 mph. Alice's car is going 60 mph towards Bob. Bob's car is going 60 mph towards Alice. No one is exceeding the speed limit but their relative velocity is 120 mph. The gap between them is also closing at 120 mph which a person on the side of the road witnesses. The closing speed equals the relative velocity except for an insignificant relativistic effect. But with higher relativistic effect, the closing speed gets up to two times the relative velocity. Bob and Alice could see their relative velocity is also 120mph with radar guns. I just don't see how two cars headed towards each other wouldn't crash at twice the speed as one would being parked and the other hitting him at 60mph. That's how head on collisions work. If what you're saying is true then we live in 2 different physical universes.
Agree with gap closing at 120. Alice moves 30 mi in 30 min, v=60. Bob moves 30 mi in 30 min, v=60.
Note, they move simultaneously
We have accounted for all objects in motion. Where is the thing moving at 120?