There is a setuid bit on the file.
user@host:~$ ls -l /bin/mount -rwsr-xr-x 1 root root 40152 May 26 19:31 /bin/mount
Why does operating system require root access to execute the 'mount'?
user@host:~$ /bin/mount /dev/sdb1 /mnt mount: only root can do that user@host:~$ sudo /bin/mount /dev/sdb1 /mnt user@host:~$ lsblk | grep sdb sdb 8:16 0 102M 0 disk └─sdb1 8:17 0 101M 0 part /mnt
# / was on /dev/sda1 during installation UUID=026bb2d9-1c0c-4163-85a1-f83b2221eb34 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=aec6b039-13b1-4568-abb1-2be1f3429325 none swap sw 0 0