With time the system in vehicle traffic control must also get updated else it would be easier for hackers to break it. But upgrading the system would lot of cost and also its government 's so it might take time. IT would interesting to know when was last the software and hardware used in vehicle control system was reviewed and reconded for upgrade.
The main problem is that each government entity sets its own standards so there is not much commonality, and less chance to reuse IP. Many systems in use are over 20 years old, and the expense to replace them is too high for the current economy to afford the cost of upgrade.
Another example of the asymmetric arms race that we experience with digital controls. A determined hacker can reverse engineer and break into systems faster than the infrastructure can be replaced and secured. It is unfortunate that money has to be spent for such purposes rather than for projects that provide direct social benefits. I hope that the people configuring the next generation of secure systems are thinking ahead a few steps: if a traffic control device were stolen, how quickly could the security protocols be reverse engineered and spoofed? We need our infrastructure to be secure enough that the hackers will devote their energies to other targets.