Well, consider this:
"Certain jobs are regarded as so distasteful, that they are filled by a permanent rotation system in which almost everyone serves his turn; the most notable instance is work in the kitchen and dining room, such as cooking, dishwashing, and serving..." Melford Spiro - Kibbutz: Venture in Utopia
"In the absence of private property, and of money, it is obvious that the profit motive does not operate in this society." Melford Spiro - Kibbutz: Venture in Utopia.
Think of that guy in STAR TREK 2 vacuuming the floor in the background while Spock and Kirk are chatting. Who's to say he does that full time? Maybe it was just his turn that week to clean the floors?
Also, as I pointed out in the past, Revolutionary Spain abolished money but their were still waiters doing their jobs. George Orwell and others noted this.
"Foreigners who gave a tip had it politely returned with an explanation of why the practice corrupted both the giver and the receiver." The Spanish Civil War by A. Beevor.
But in that example, the worker is still in receipt of some benefit to himself or other etc....in a society like the federation, however, there is no incentive to take part in any kind of shared society (not unless the federation withholds technology) the cleaner/waiter gains nothing from working individually or collectively that he wouldn't still gain by not working - so while you're hoovering the ship (cos you believe in the mutual benefit of such an agreement)....i would be using transporter technology to explore the world, replicating lobster and learning French cos i have the time and freedom to do so, safe in the knowledge that i do not have to do any hoovering whatsoever
Also don't assume an 8 hour day is universal. Today in France people work 7hour days/35 hour weeks, in the Israeli kibbutzim people were working 6 hour days, and during the Spanish Revolution the workday was split between two people to alleviate unemployment.
And you do know how the 8 hour day came about? From the IWW (Industrial Workers of the World or Wobblies). They advocated for the 8-hour work day/5 day work week in place of the 12-hour work day/6 day work week. They originally wanted to reduce the work week even further.
"8 hours of labor! 8 hours of rest! 8 hours recreation!" [It was something along those lines]
"...we must inscribe on our banner the revolutionary watchword, 'abolition of the wages system.'" - Preamble to the IWW.
"Give the worker the full product of his toil and his pension is assured." - 'Big Bill' Haywood (IWW Speaker).
erm...ok.....are you here to recruit or something?
I could just have easily said a 12 hour shift (the length of the shift was not really that relevant) the main point was that people rarely work because they want to (and so in a society that doesn't demand it...why do it.....i mean aside from being a good comrade)