This absolutely makes sense. It definitely is possible to generate a meaningful revenue from reasonably targeted ads at SERP, based purely on the search query.
OTOH what are you looking for may have a context. That same car dealership's ads may vary greatly in content (and click-through rate) if it is known that the person looking at the screen is a recent graduate, or has a family with three kids, or is a single at his 40s. It's hard to sell a family wagon to a recent graduate, but it costs the same to show an ad with a "wrong" car on it. This kind of precise targeting is what advertisers are ready to pay a premium for.
OTOH what are you looking for may have a context. That same car dealership's ads may vary greatly in content (and click-through rate) if it is known that the person looking at the screen is a recent graduate, or has a family with three kids, or is a single at his 40s. It's hard to sell a family wagon to a recent graduate, but it costs the same to show an ad with a "wrong" car on it. This kind of precise targeting is what advertisers are ready to pay a premium for.