“Hey look, kids, there’s Big Ben, and there’s Parliament.”
I accept as you say it being your opinion, but I don't understand why you insist they are dangerous - even ignoring that anyway it's not the roads but drivers who are dangerous.
There must be very many thousands of roundabouts all over the UK, many built a long time ago; from Motorway junctions with the "ordinary" roads (the r'bout itself is formed by bridges above or below the motorway, not of course, on it), via joining dual- and single-carriageway A-class roads, down to small "mini-roundabouts" comprised of a low, white-painted hump on the asphalt in town-centres and housing estates.
There is a definite technique, taught by driving-schools and advanced-driving courses, for negotiating them; but if roundabouts were genuinely as dangerous as you claim they would be the site for the majority of road accidents, and would have been replaced decades ago.
Driving on any road is hazardous, but excessive speed, reckless over-taking and pulling out of side-roads without looking, are among the main causes of crashes; not junction types. You can't just single out one type of junction and condemn it in such a blanket fashion just because you don't like it.