There's no shortage of developers, but big tech companies are attempting to increase the supply of developers to reduce the cost of developers?
Open markets don't have shortages, those are caused by price controls. In a market the product is always available to the highest bidder, unless there are zero suppliers at any price which is obviously not the case here.
But "shortage" sounds like a problem that needs to be solved by some kind of external intervention, whereas "wages are high" is more of the sort of thing people like to see in the economy, and is not actually a problem at all because the high wages on their own are sufficient to attract the necessary talent to the industry.
They may be able to hire more devs if they increase salary, but this would mean that the price of the end product would become too high, and they would go out of business.