There actually was a law that prevented this. The Smith-Mundt Act of 1948. Passed with huge bipartisan support, in the aftermath of WW2, it prevented the US govt from using domestic media sources to broadcast propaganda or drive narratives inside the US. It was passed, as the legislative history shows, to give assurances to US citizens that what happened in Germany could never happen here.

The law actually worked quite well and stood as a silent sentry for 75 years. But it needed to be gutted, to allow for what was to come. So in 2012 the Obummer administration slipped the gutting into the massive Defense Authorization Act. Which nobody reads and generally passes on a voice vote with little or no debate. Obummer then took the unusual step of signing the bill with no fanfare while on vacation in Hawaii with Big Mike. Before anyone could figure out what had been done.

The changes essentially allowed the government to treat its citizens like they treated citizens of foreign enemies. Using and paying the media to broadcast the messages they wanted you to hear, and censoring opposing views. This was on full display, of course, with the Covid narrative. Hundreds of millions of dollars (that we know about)paid to the media and Big Tech to drive the narrative and suppress dissent.

If you ever wondered how all of that came about the elimination of the Smith Mundt Act protections tells a large part of the story.