There should be no cause for surprise. If you ask chown to recursively change the ownership of a directory, /a/b/c, chown will change the ownership of that named directory and any files and directories below it, such as /a/b/c/d and a/b/c/d/e. It will not change the ownership of files or directories above /a/b/c, such as /a and /a/b.

What you've demonstrated above is equivalent to using chown on /a/b/c and then using ls to inspect the ownership of /a. /a will not be affected.

Regards,
Alister