Accordion buses in London

When you think of buses in London, almost everyone will say double decker buses. But these days, we find long single decker buses that are connected by something akin to what you find on accordions (this allows the bus to bend in the middle). Why have they introduced these? They are really a menace on the roads to pedestrians and other cars. Someone who allowed these things to be introduced on the streets of London has made a grave mistake.

The only reason why they still infiltrate the streets is because they cost a lot of money to put them there. I suppose no one is going to be brave enough to take them out of service. Or could they? Well, no.