They have the same problem with the demand side. In the event of a supply shortage, their solution is "demand less" and not "supply more."
While "demand less" works in the short term, if the demand isn't met by an increase in supply, and if prices are capped, "demand less" doesn't work, and new supplies aren't ever brought to market, resulting in over-use of the current resources to the point of unprofitability, after which point government is forced to step in and subsidize supply, granting exceptional powers to the government in the process.
Sounds like Liberal Plan "A" to me.