you're asking for a 'source' on a foundational axiom of political theory. do you want a source for 'all governments have laws' too?
a state is defined by its monopoly on violence, enforcing that is inherently authoritarian.
switzerland has police, prisons, borders and is structured around protection of capital and property rights.
'democracy' under capitalism reflects the interests and prejudices of those with property. it is plenty authoritarian if you are not in that class.