I think part of it is there's a distance between executives and the departments. They assume that if everything is currently working, there's enough redundancy in place, even if that's not the case at all and people have just been sticking around a bit too long for various life reasons.
I know in my department, it will only take two people leaving to effectively kill the department (myself being one of them), as there's no one else still here who knows enough about the software to support it (there's only four developers in the department, two being temporary help from an office in India)
And I'm interviewing right now, so soon they'll be down to one. How they thought they could get away without letting us train other people in the department for so long when we're supporting software that generates millions of dollars of revenue for large clients they don't want to piss off every year I don't know.
I pushed and asked for a raise for the past three years and have gotten none "Nothing we can do, times are tough right now." I'm sure they'll suddenly find something they can do once I leave, but then it's already too late.
They've even got several big development projects my bosses' boss is pushing for on the horizon, and still trying to do it without any hiring or knowledge transfer. It's idiotic. Large corporation too.
But I'm sure none of the executives knows this is the case with this department, especially since we're one of the smaller ones.
I already have stuck around three more years than I intended to. One of those years I was preparing for our wedding and too exhausted to make other life changes, then I wanted to relax for a few months, then right as I was starting to interview the pandemic came and I decided to stick with my safe and fully remote job a bit longer.
Sucks because if the department dies that will leave about 80 people in limbo (that's about how many non-technical people in the department right now), but I'm done fighting and failing to get more people in the department, and I'm not willing to keep supporting it anymore.