[scottishtv]

Why does UK have a lack of live cameras?

As others have said, the main reason is because they wouldn't get used much.

In the States you've obviously got a lot of city and regional stations with many rolling hours of local news/weather/traffic per day and ad breaks every 8-10 minutes - lots of transition shots to fill and utilise outdoor cameras. The main BBC/ITV regional news bulletins are one single structured 30-min bulletin at teatime, with 10 mins or less at both lunchtime and late, and 5 min updates at breakfast.  There's basically no time to casually 'take a look outside' and the weather forecasts are quite brief.

With just over an hour of regional news on the main broadcasters on weekdays, there's even fewer instances to use live cams in and out of commercial breaks as only the ITV regional news has one.

There are of course live shots behind the presenters on a lot of regional news as part of the sets, but even those can upset people who live in other percieved 'less important' part of the region if you focus too much on one town or city.

As for weather, the BBC introduces national and regional weather with a picture from their very busy 'Weather Watchers' community.  I guess this is the closest comparison to some of what I see on US local news.  It's still brief though:

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As for Downing Street, when there's a political scandal brewing there will often be a camera set up for hours on end outside pointing at the door, but I believe that's always manned. All of the property around there and on Whitehall is government owned so I doubt they'd grant permission for something more permanent to be installed.

As for other cities, live shots might be intesting for occasional building fires etc. but these are rarely treated as breaking news stories here, so the next scheduled bulletin will typically utilise video from social media - which is usually much closer and from multiple angles.