I think the worry is precisely that bias on issues is so deeply embedded in the culture of what is when all's said & done an Establishment institution that 'conscious decisions' are not required. Whether it's the US-centric world view complained of in the OP or the obsessive coverage of every Royal belch, 'what matters' - ie, what counts as news - is so taken as read by the overwhelmingly private school>Oxbridge Beeb that no directive is necessary.
To what extent this causes and to what extent it reflects attitudes in the population at large is a chicken & egg debate that can go on long into the night. But there's certainly been more than one case to answer, such as the notorious occasion during the miners strike when the BBC admitted 'a mistake' in reporting events at Orgreave:
The miners were not fighting, in fact it was a hot sunny morning and they were mostly lazing around when, without provocation, the police launched what amounted to a cavalry charge against them. The miners obviously responded in kind, and attempted to defend themselves from this police violence.
In a BBC news report later that day, in a case which is famous in media studies research, the BBC changed the order of these two linked events. The police charge that provoked the miners, was shown after the the miners response, so the unaware viewer would assume the police were responding to violent miners and not the opposite, which was the case.
The BBC now admits they ran the footage out of order, but claims it wasn't deliberate.
http://bbc911confile.blogspot.co.uk/2008/09/orgreave-miners-strike.html
I'm a long time fan of the BBC, and consider it one of our greatest assets and achievements - almost up there with the NHS. But when it comes to the news, (where, let's face it, the notion of objectivity or impartiality is a logical absurdity), its Establishment credentials do tend to show through.