Very very basic conceptual question. (Obviously from a beginner)

I want to manually mount an internal hard drive.

My drive in not mounted.

dir /media is empty.

I click on the drive in the GUI, it mounts.

Now /media has /media/myDrive

myDrive is sda

But, to manually mount my drive using mount, I know I am supposed the mkdir mountpoint in advance, so that I can do

sudo mount /dev/sda /media/myDrive

Question:
How come if I use the GUI, the mountpoint does not need to exist in advance?

If I want to mount my drive in a script, do I absolutely must mkdir /media/myDrive in advance?

Many thanks for clarifying a newbie misunderstanding.