As was mentioned upthread, the idea that Detroit, Cleveland etc don’t have NFL teams was a little joke. The fact that Detroit, Cleveland, etc play in downtown stadiums within the city limits has also been mentioned.
Back on topic, while I agree that stadiums are boondoggles for the taxpayers, I wouldn’t go so far as to say that the LA voters are smarter than their brethren in the rest of the country when it comes to voting them down taxpayer-funded stadiums. I’d say its more that the proposals for stadiums in Los Angeles haven’t yet had politically powerful, well-bankrolled supporters behind them pushing for them. Arlington Texas voters got steamrolled by Cowboys owner Jerry Jones, for instance, which is the type of power the LA voters haven’t faced yet, IMHO.