In Dolphin, I am able to mount a external hard drive without entering in a password, however I am not able to mount an internal hard drive partition without entering a password, how can I set it up so that I do not have to enter a password when mounting an internal hard drive?

P.S.
I think the answer has something to do with polkit-gnome-authorization or like.

if it's an internal drive why not just mount it in fstab?

see https://wiki.archlinux.org/index.php/Ud ... ormal_user