The BBC is bound by its charter to be unbiased and objective. ITN relies on advertising revenue for its existence, so must maintain trust with its viewers. Channel 4 is a publicly owned, not for profit, commercial enterprise who similarly must retain trust.
GB News is owned by a small number of wealthy individuals. People it seems have political, alongside financial, motivations for the channel. Insight can be gained by reading what Andrew Neil said when he resigned so shortly after its launch.
“What I didn't want it [GB News] to become – I could see it was happening, which is why I left almost immediately – was an outlet for bizarre conspiracy theories or anti-vaxxers or, basically, the nutty end of politics', further describing what he saw as a drift towards the style of the US network Fox News, telling peers such a drift would be 'bad for Britain' and describing the channels production values looking 'as if it were coming from the nuclear bunker of the president of North Korea”.