Alarm systems in 1981

It was expensive for private homes at that time but already fairly common for businesses. They had emergency buttons that used phone lines for banks as early as the 60s. They were usually a direct line, but all an alarm system needs is a simple electronic dialer and a phone line.

I am a little surprised at the lack of closed-circuit security cameras in all these places.

Of course, I was a teenager in 1981, so I didn't have a real job in a bank or anyplace with a vault, but it seems to me that a place like the Big Heist would've had cameras coming out the wazoo. (In my local Subway, a place that seats maybe 18 people, there are no less than six security cameras... and it's only a fast food joint! That place had over $4 million in diamonds!