How to access USB serial ports as a non-root user?

[DonK]

Why is it a bad idea to change /var permissions?

$ sudo echo 'perm cuaU* 0666' | sudo tee -a /etc/devfs.conf
$ sudo echo 'perm ttyU* 0666' | sudo tee -a /etc/devfs.conf
$ sudo service devfs restart

$ sudo chmod 777 /var/spool/lock
$ sudo chmod 775 /var/log
$ sudo chmod 660 /var/log/aculog

$ tip ucom1h
connected
~

What's wrong with adding a user to the dialer group?

$ sudo pw group mod dialer -m don