A shortage is a situation, where the market cannot bring high prices down by increasing the supply. For example, if software engineers earn more than equally demanding roles in other engineering fields and the situation persists long enough, there is a shortage of software engineers.
Who decides if the price is high or low? That should be the market. High salaries -> more people decide to pursue it as a career -> more competition -> lower salaries. They are trying to force salaries down quicker
