You could argue that today's circumstance is why you DON'T need explicit laws prohibiting workplace monitoring.

Anyone with the desire could set up such systems today. But they don't. Because they're expensive, inaccurate, and ultimately not all that useful in the social context. There are places that do employ such monitoring, but they're a corner case.

Trust is a core commodity in the workplace. It's usually more profitable to establish a trustworthy workgroup to accomplish some goal than it is to accomplish some goal WHILE monitoring the workgroup's every move for infractions.