So long as the speed of light is an ultimate speed limit, the only way to ensure identical latency is to make everyone experience the same latency as the person

So long as the speed of light is an ultimate speed limit, the only way to ensure identical latency is to make everyone experience the same latency as the person with the worst latency since every 1000 miles of straight-line distance adds 5.4ms one-way latency under ideal conditions. So a signal following undersea cables will incur worse latency as it's not a perfectly straight line point-to-point. Better communication technologies can get us closer to that ideal, but everything we know points at the speed of light being an upper bound for any signal propagation.