Just a guess. I'd imagine they need low-time people that can hack low pay and a brutal environment. They have to be able to fly a single-engine NDB and land on top of Pike's Peak with a dead captain, without reverse, the other engine on fire, and with the mask on.
My sidebar, I think a lot of flight instruction has gotten watered down in the last decade. I think the failure rate at Lakes is good. They know that can't just pass people and be on their merry way. Never wanted to go through any of that, but Lakers are always at the top of my list. What and how those people do what they do is almost beyond what I can comprehend.