I am frankly baffled by your idea that a dictatorship would not be oppressive because no money is in use in a society. If anything, both common sense and historical experience suggests that the opposite is true. You might want to refer, for instance, to Lenin's attempts at "war communism" in 1918-1920, or Cambodia under Khmer Rouge. As for common sense, in the absence of a market the government is left as the only institution controlling the distribution of goods. The total dependency of the citizens on the government for their very sustenance creates a wide scope for the most heinous abuses. You might want to refer to the experience of Soviet and Chinese labor camps, which are quite similar indeed to your notional society (the difference being that Soviet labor camp inmates cleared forest, not old cities), and closer to home to the various 'prison' experiments conducted in the sixties and to the experience of the original Plymouth colony, which is described in the diaries of Governor Bradford and is so relevant to your question in more ways than one, as I hope you'll see, that I feel justified in quoting it extensively. The colony's articles of incorporation are on pp. 45-46 of the linked edition, of which §§3, 5 and 10 are the most relevant (converted to modern spelling):

3. The persons transported & the adventurers [investors] shall continue their joint stock & partnership together, the space of 7 years […] during which time, all profits & benefits that are got by trade, traffic, trucking, working, fishing, or any other means of any person or persons, remain still in the common stock until the division.
4. That at the end of the 7 years, the capital & profits, viz. the houses, lands, goods and chattels, be equally divided between the adventurers, and planters […]
5. That all such persons as are of this colony, are to have their meat [food], drink, apparel and all provisions out of the common stock and goods of the said colony.

The colony worked on these principles, without, as you see, money exchange or true private property, for two years, after which it was on the verge of starvation (page 130) because people didn't want to work hard in the common fields. There being no possibility of procuring food from anywhere outside the colony, Governor Bradford was forced to violate the articles of incorporation, to distribute land etc. into private use and to re-form the family units effectively disbanded under article 10 (pp. 134-136 of the linked edition):

All this while no supply was heard of, neither knew they when they might expect any. So they began to think how they might raise as much corn as they could, and obtain a better crop then they had done, that they might not still thus languish in misery. At length, after much debate of things, the Governor (with the advise of the chiefest amongst them) gave way that they should set corn every man for his own particular, and in that regard trust to them selves ; in all other things to go on in the general way as before. And so assigned to every family a parcel of land, according to the proportion of their number for that end, only for present use (but made no division for inheritance), and ranged all boys & youth under some family. This had very good success ; for it made all hands very industrious, so as much more corn was planted then otherwise would have been by any means the Governor or any other could use, and saved him a great deal of trouble, and gave far better content. The women now went willingly into the field, and took their little ones with them to set corn, which before would allege weakness, and inability; whom to have compelled would have been thought great tyranny and oppression.

Governor Bradford then continues with a discussion of the reasons for this:

The experience that was had in this common course and condition, tried sundry years, and that amongst godly and sober men, may well evince the vanity of that conceit of Plato’s and other ancients, applauded by some of later times, that the taking away of property, and bringing in community into a commonwealth, would make them happy and flourishing; as if they were wiser then God. For this community (so far as it was) was found to breed much confusion and discontent, and retard much employment that would have been to their benefit and comfort. For the young men that were most able and fit for labour and service did repine that they should spend their time and strength to work for other men’s wives and children, with out any recompense. The strong, or man of parts, had no more in division of victuals & cloths, then he that was weak and not able to do a quarter the other could; this was thought injustice. The aged and graver men to be ranked and equalized in labours, and victuals, clothes, etc, with the meaner and younger sort, thought it some indignity and disrespect unto them. And for men’s wives to be commanded to do service for other men, as dressing their meat, washing their clothes, etc, they deemed it a kind of slavery, neither could many husbands well brook it. Upon the point all being to have alike, and all to do alike, they thought them selves in the like condition, and one as good as another; and so, if it did not cut of those relations that God hath set amongst men, yet it did at least much diminish and take of the mutual respects that should be preserved amongst them. And would have been worse if they had been men of another condition. Let none object this is men’s corruption, and nothing to the course it self. I answer, seeing all men have this corruption in them, God in his wisdom saw another course fit for them.