Star Trek economics

As Utopian as 23rd/24th century Earth appears, I suspect
there may in reality be a darker side. Money appears to be
no object although it does in fact still exist, implying
some remaining monetary elements.

[for sources I am using, as they are generally all
self-consistent, all the Star Trek feature films bar
the stupid Nokia JJAbrams abomination; the Next
Generation; Deep Space Nine; and Voyager]

However, on Earth at least money is not needed.

Part of me suspects a sinister side to this, mainly
because I cannot personally reconcile a centralised
government with a voluntary economy and secondly
because the economy is not entirely voluntary
because money is often mentioned!

This sort of leads me to allow three conclusions:
1.People work, for free, and all goods/services
are also free (more or less) but the unemployed
have three options: Prison! (or 'Reeducation Camps'),
to join an offworld colony or join Starfleet.

2.That there is paid work of a sort in that
individuals working for Starfleet or the Federation
get some sort of allowance or renumeration.
I'm assuming that there is a tax on certain
traded goods which pays for all this.

3.Some form of market economy does exist, possibly as
described in http://legalsmeagol.blogspot.com/2010/07/sci-ficonsensus-economics-or-part.html
but large estates etc are Federation owned, while
voting rights, free healthcare and education* are only
available to individuals and families who work for
the Federation in some way.

Housing may or may not be freely provided although
presumably it is along with food and medicine via
public and private replicators. It is implied
that all means of production are owned by the Federation
in some way.

*I'm extrapolating/ripping off the novel/'manifesto'
Starship Troopers by Robert Heinlein, readers may
also check out "Forever Peace" by Joe Haldeman.
Both show a very dark side to state collectivism.