They exist for many reasons:

Inside these lists, you will often see a link at the very top labeled "Parent Directory."

Look for results that display "Index of /" in the title and list URLs containing IP addresses or terms like /media/ , /videos/ , or /shares/ .

Thus, the open directory persists as a , not a bug.

Regardless of intent, once indexed, these links remain in Google’s cache for weeks or months.

Google Index of Series Parent Directory: How to Find Free TV Shows Using Google Dorks

Similar to Shodan but with a more academic bent. Great for finding open assets belonging to your organization.