You misunderstand the word "news".
In the US, the advertisement ridden cancer that masquerades as news is essentially a copy of the police blotter. This means any law enforcement action, from the trivial to the tragic, is reported in excruciating detail. The sole purpose of this exercise is to keep white middle class voters shiat scared and voting for whichever politician promises them "safety".
To achieve this saturation hysterical coverage, the U.S. News channels use helicopters. The typical stories reported by the "eye in the sky" are traffic jams, traffic jams, traffic jams and very, very slow car chases. They also like to show prurient coverage of suicides and accident victims, but these are few and far between. Being a highly competitive market based on advertising revenue, once a local news station acquires a helicopter, all the rival channels are forced to follow. This has the obvious effect of diluting the value of any news story and for example, any major road accident will have at least 2 or 3 news helicopters hovering over it like the proverbial flies on shiat.
So, to answer the question, the reason the UK has few news helicopters is because for today at least, the business of news reporting is not based solely advertising revenue or the need to scare people into voting for corrupt politicians. The shock value of filming dismembered bodies at RTAs has,for the time being, escaped the attention of news desk editors in the UK with their room temperature IQs.
Hope this helped.