Even in Paris and Florence, newer areas don't have issues.That's why I emphasized "some European cities". You know Paris and Florence are European cities, right?
So - the operative word should be newer/older areas in all cities.
Most of the world cannot demolish older neighborhoods and make wide boulevards at the whim of the central govt.
They have preservation laws on the books. For tourist business or simply for preserving the look of older neighborhoods (which are worth preserving).