The 70s are the decade where there were many hijackings. That's also when air travel became more commonplace and huge jets were more widely in service.
In the 60s if you weren't a military person, foreigner arriving from or headed to home, or white guy with a suit, you'd be picked up on pretty quickly, security checkpoints or no. Also, we weren't exporting trillions of dollars to and fomenting unrest in the Middle East in those days.
In the 90s, I used to fly to Baltimore on Southwest to get drunk for $30 with friends for the weekend. If I couldn't make it, I'd give the ticket to someone else or sell it. Totally different universe and threat model than ye olden times.
In the 60s if you weren't a military person, foreigner arriving from or headed to home, or white guy with a suit, you'd be picked up on pretty quickly, security checkpoints or no. Also, we weren't exporting trillions of dollars to and fomenting unrest in the Middle East in those days.
In the 90s, I used to fly to Baltimore on Southwest to get drunk for $30 with friends for the weekend. If I couldn't make it, I'd give the ticket to someone else or sell it. Totally different universe and threat model than ye olden times.