Stupidity: When Gary 7 learns that agents 201 and 347 were killed in an automobile accident, he must take over the mission and save the earth from nuclear war. However, their technology allows them to transport anywhere they want through the vault device. It makes no sense for both agents to drive to McKinley Rocket Base when they could have easily transported there.
Suggested correction: Good point, but it seems more likely that 201 and 347 were executing a careful plan that depended on their cover as normal humans acting normally. Using transporter technology risks discovery. Gary Seven only used the vault transporter as an emergency measure, missed being observed materializing by mere seconds, and was detected by a guard moments later. Same for Kirk and Spock.