They elude to it in the second line after the title but they never point it out:

Five years ago it was a lot easier to buy a car for less than $30,000.

...and later in the article....

New cars costing less than $30,000 were just 13.9 percent of all car sales in the first half of this year; for the first six months of 2019—before the pandemic drove up new car prices by so much—they made up 38 percent of new car sales.

I think the answer is simply inflation:

$30,000 in 2019 is worth $37,722.15 today

...and...

$24,000 in 2019 is worth $30,177.72 today

So for apples to apples comparison the question should be, "How many fewer cars costing $24,000 in 2019 are there that cost $30,000 today?", but the article doesn't ask or answer that question.