I think you're wildly overestimating the intelligence and awareness of the general population.

The media is and has been doing this for decades. If they do it in a totally obvious and outright manner, then yeah, everyone's going to notice, but if they do it in a more subtle way and push their agenda over a longer timeframe, most people won't notice that, or they'll only notice it when it's too late. It's not about brainwashing everyone. All you need is a critical mass and once you're there, you've basically won.

Most people lack critical thinking abilities and they're rather contend with having other people think for them. You don't notice this here on HN because the readers and commenters here are far smarter than the average person is.