There was no military wide policy change. The AF was first, way back around 07, then the Army, then Navy and USMC was the last to get rid of base passes in 2016. There was no executive order from Obama or Bush. Each service made the decision on their own. Base passes were only started in the 70's, and they outlived their usefulness. It is more important to identify the PEOPLE, than the CAR.
For people working under a contract, the company provides all the information on their employees to the base, including names, DOB's SSN's, security clearance, dates, etc. I have had to liaison with many contractors to ensure base access for projects I was working on.
You feel the changes - from cars to people - made us safer? Sounds about right...