Why do you think people are so heavily influenced?

Simply because most people are fairly stupid and companies and governments have spent decades, if not centuries, finding ways of getting people to do what they want them to do in such a way that they think they are making the choice themselves. Also people are so stupid that what would previously have been left up to people to work out for themselves now has to explained to them the feedback on this is that people don't think for themselves and expect to be told what to do in every situation.. this makes it very, very easy to control people and as a result influence them.