There's a lot of intentional bias in both mainstream and social media - but there's also a lot of what I'd call unintentional bias - coming from a number of influences. One is the fact that 80% of journalists come from professional or upper-class backgrounds. Only 7% of people attend private school in the UK... but half of newspaper columnists are privately educated, 47% of political commentators, 45% of leading podcasters and 38% of BBC executives. Media professionals, their families and friends, their whole life experience and perspectives, are at the heart of the Establishment. Another influence is the self-censorship that inevitably infects an industry largely owned or influenced (for example by the need to attract advertising) by wealthy corporations and individuals. Even journalists free from specific pressures from media owners, etc, and trying to do the right thing, know that their career advancement depends on not doing it too enthusiastically. Then there are unquestioned 'professional' assumptions. Dramatic beach scenes of asylum seekers are preferred over presenting accurate statistics because they're 'televisual', they 'come across', boost viewing figures, etc... In itself, each clip may not be inaccurate - but cumulatively, by the very fact that they are selected as 'news', they create the impression that there are lots of such immigrants - but in fact there aren't. Deepest of all, perhaps, is the 'automatic' bias of the idea of news itself. By its very nature it's bad. Most people living pretty harmoniously with their good neighbours, in their supportive communities, are not newsworthy - nor indeed are they good grist for fictional dramas - so people that are more socially isolated, and therefore nowadays more dependent on media interactions, get the impression that most people are unkind and violent, and must be controlled by Authority. And it is in fact true that social isolation tends to move people to the political right (and that sociability moves them left).