Based on the article, it appears that the blacklists are used to punish instances where someone was ordered to pay a fine but didn't comply. I think in pretty much any western country, that would result in a prison sentence in itself, but apparently not in China. So those limitations that are put on blacklisted persons are essentially a half-prison: not complete restriction of movement, but enough to serve as punishment. From that viewpoint, it might actually be cheaper to enforce than a prison sentence. It certainly seems to be preferable to the Chinese authorities who came up with the system.