"some 40,000 people per day are hit by "A" car". How can you possibly read this and think this was about the all cars on the road?

Sorry for being cheeky but the parent literally just addressed your question.

I don't understand why we're arguing about this when a simple Google search reveals the answer.

"It is estimated that an ambitious bear may consume in excess of 10,000 moths per day, with some estimates ranging as high as 40,000 moths per day."

"One group of scientists analyzed bear scat and revealed that a foraging grizzly could gobble 40,000 moths in a day."

"Hit by cars" means multiple cars. "Hit by a car" suggests one car. We're often sloppy, and often there's an implicit understanding that contradicts what's said directly. Clearly this is silly, one car can't do that so we interpret.

Neither figure seems particularly compelling here, of its "eaten by bears" it seems way too small if it's "eaten by a [single] bear" it seems too big.