The theme of this article is the extinction, or near extinction, of drive-in theaters in the US, once ubiquitous across the America (I'm somewhat surprised that there is even one still open). This theme pervades the article, note the words used relating to this theme: nostalgia, since childhood, lie down on the roof of the car, reminds me of growing up, the fresh air, the picnic. The sentence in question again relates to the theme.
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