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LOL!

First you're implying the US has lots of residential high rises. Compared to Canada, for example, there is much less in MOST cities. The rest of the world, including very Americanized places like Canada never had the 'white-flight' after WWII, or at least not to the same extent, so instead of the rich or otherwise middleclass (not necessarily white-rich/middle class) moving out to the outskirts, more stayed central, increasing density. Go ahead, compare Calgary, Alberta and Austin, Texas's skylines, you wouldn't know the two are the same size. The US, instead ripped up neighborhoods and urban fabric with freeways and road widenings, destroyed trolleys, and just saw the downtown as a business centre. So most downtown skylines are comprised of office buildings in America.