Surveillance is orthogonal to camps. They could build the camps first and start dumping in undesirables and then start surveillance immediately after, for all we know.

It takes time to build surveillance capacity. If they build the camps first then people can pick up their pitch forks and organize a resistance before it goes anywhere. If they build the surveillance first then the day the camps become public they already have a list of all the prospective resistance leaders to round up and everyone else is too afraid to express opposition for fear of creating evidence of a lack of fealty.

The problem with widespread surveillance isn't that it's inherently malicious, it's that it's inherently dangerous. Because most people are good, the potential it creates in the hands of a good leader to catch evil terrorists will always be less than the potential it creates in the hands of an evil leader to catch good freedom fighters. It's a tool for the concentration of power. And it shrinks the time lag during which to mount a resistance between when someone malicious takes power and when the whole world is on fire.