First thing to note is that while the pictures are from the 1960s, the article merely says that Ford uses (and has used, for years) these caves to store cars in transit.

The Kansas City Ford plant manufactures more trucks/vans in a day than it can ship to their destinations, and Ford uses almost any surface lot it can rent (including a nearby amusement park's lot in the offseason) to hold cars until they can be transferred by rail or truck--it's very demand-driven. It's completely natural they'd use these caves as well based on their proximity to the rail and interstate transport near the river.

I don't see in the article anything that implies there's a cache of 1960s cars down there gathering limestone dust. That space would quickly be reclaimed for temporary storage of Transit vans awaiting their buyers.

There's a Ford manufacturing plant 3-5 miles from many of Kansas City's limestone caves along the Missouri river. And as the comment-linked video down below shows, these warehouses are vast and even used for commercial businesses. You can play paintball in a cave at Subtropolis.

Not too far away (3-4 hours), the salt mines in Hutchinson, KS store a lot of Hollywood memorabilia.

One big plot point of "The Day After" back in the 1980s was that people sought shelter in the underground caves around Kansas City.

Because Ford now have a large number of factories and other facilities deliberately located near the caves so that they can keep on using them as storage for new vehicles that need to be stored before they are shipped to customers.