Can you link three examples.

Here's an example: https://arxiv.org/abs/1611.06999

I believe the PDF link is only removed after a paper has been withdrawn. But if you click on v1, you can still access the original paper (incorrect, in this case).

v2 is a 0kB file. As you note, v1 is still available, just as with any other paper that was updated.

In any case I don't think that withdrawn papers support the OP's claim that PDF links are hard to find for normal papers.