not at all
how about a little bit of basic urban planning education?
it is because london evolved as a town adn then city, deleoping from rough tracks and trade routes that related to most navigable river routes and land-tracks.
also, the notion of a cartesian grid layout for cities only developed in much later, and once a city has a medieval plan it is very hard to fit a grid to it after, especially around monuments and major buildings.
hence why most european cities introduced grids after major disasters [earthquake and fire in lisbon's case, for example]. in paris, baron haussman was given carte blanche to work on the city and while he widened routes to major buildings he did not introduce a pure grid as it was too hard to fit to the existing structures.
new york, like the majority of us cities i believe, was a much later development and could use a pure grid system from the outset, allowing what was in reality an urban planning 'idea' that had only been tested in small 'experiments' [lisbon, barcelona etc] to be tried from the beginning.
london briefly toyed with a grid after the fire of 1667 but implemtation was slow and eventually a reduced version of the haussman ideas [widened boulevards and openend squares as seen in paris and rome].
if you want to be brutal it is because the european cities have a greater history. neither planning system is better than another, if the ancient city plans were unworkable then they would have been abandoned and grid layouts advanced earlier, especially during the renaissance when ideas of pure geometry and proportion were developed.
if you want to know more about the evolution of cities, layouts and urban planning then a good start are the spiro kostov books.