Non la traduzione, fino a li ci arrivo anche con il mio scarso inglese (almeno credo), ma proprio il senso "tecnico"
Questa storia che in init 3 sei implicitamente aggiunto in quei gruppi mi mancava.
When you boot in runlevel 4 "graphical login", you need to add your
user account at least to the following groups:
- audio (so that you have sound),
- plugdev (so that auto-mounting a CD or USB stick works),
- power (so that you are allowed to power down your box),
- floppy (if you have a floppy drive and want to use it),
- cdrom (if you want to be able to access the DVD you just inserted)
This is the difference with runlevel 3 "console login": in runlevel 3
you are implicitly added to all these groups when you login. In
runlevel 4, you must be explicitly a member of these groups or else
you will not have access to your computer peripherals.