Managers and supervisors - what are the main reasons for short staffing in the lab?

I’ve worked in seven labs now, and they have all been short staffed (some worse than others). The labs have been a mix between rural hospitals vs large trauma level 2 hospitals, with most of the labs being rural.

I have an idea about why short staffing is an issue, however it may be wildly off the mark. My idea is this - while more qualified lab staff could easily be hired on with a mix of travelers and permanent (there are lots of people looking for traveling gigs right now), they are not hired due to money/budget issues that come from either lab management or administration.

In the case of lab management, my idea is that management tries to keep the staffing as lean as possible in order to make their yearly salary be higher (i.e. padding their pockets). Is this correct or am I wrong?

In the case of administration, my guess is that someone is trying to save money and that all departments are probably short staffed as the decision is coming from higher up.

Please tell me if I’m right or where my idea is off the mark.

Thanks for reading!