Making roads safe to drive as the highway code expects them isn't on the agenda for most road planning in London. I can think of countless turns where it is expected of motorists to turn left from the middle lane across a bus lane if they wish to go left. Impossible to pass box junctions that encourage rapid acceleration when a gap is seen on the other side. Not to mention roads that aren't correctly marked as it would make bus routes illegal, for example placing a road narrows sign would make driving a bus along that route an act of ignoring the road is marked as unsuitable and doing that each time a bus goes by isn't good for tfl so you won't find any narrow road signs in London.