The criticism Bland is presenting is directed towards the lolbert notion that market mechanisms operate as a form of "economic voting" and that prices serve as a "signal" for what is wanted in society.
Bland argues that "demand", as described in the analysis he critiques, is really something he calls "effective demand", which is just the amount of money that consumers with money are willing to spend. "Demand", in Bill's argument, does not refer exactly to the "demand" in the concept "supply and demand", but instead the average of the wants of the population.
With the example of people protesting for bread, Bland maintains that, unless the protestors had money, there would be no "effective demand" - demand that the market system actually cares about.
Bland then argues that, because production is oriented towards "effective demand" and not the wants or needs of society, irrational shit like empty houses and a homeless population exist because housemakers are not building houses to address society's wants or needs but instead "effective demand" (housemakers are producing for profit).
This paragraph essentially explains the difference between production for profit (capitalism) and production for use (socialism).
Further examples demonstrate the validty of Bland's statements. Take, for example, extortionate practices such as price gouging, in which companies raise the prices of commodities that are suddenly highly wanted because it maximizes profit, even when there is sufficient supply, or how some companies will take a product and essentially repackage and sell it at higher prices.
Capitalism is a system that encourages the production and selling of any kind of commodity regardless of its utility to society. This is why GDP/c is a shitty metric for the standard of living. More GDP/c exists when a healthcare system involves unnecessary transactions fostered by bloodsucking insurance companies than when a healthcare system is highly subsidized or is paid-for by the consumer directly. More GDP/c also exists when people buy cars enmasse to get to work rather than use public transporation.
Hope this helps