Americans are also the primary target it's all adjusted for. Ads are a social mechanism.
Even ads for non-American audiences sometimes copy ads aimed at Americans in various detail which doesn't make sense there.
Somewhat similar to perception of fashion differing between living in a big city or in a rural area. In a big city everything is happening around you. In a rural area you learn of things happening, might get interested, might not.
OK, I might be simplifying things.
