As somebody who has sadly had to make hundreds of candidates write on a whiteboard, here are problems I’ve run into getting the candidate a laptop:

* IT just fails: they’re unwilling to supply it, there aren’t enough, the current laptops on hand are junk, or the default password is wrong. These all happen with HR buy-in and funding.

* Recruiting just fails: they “have to move the candidate fast because of a competing offer,” they tried to work with IT but IT blocked them, they got laptops themself using their own budget but then ran out.

* I failed: I didn’t make time to prepare a non-whiteboard question, I didn’t tell my manager in each and every 1:1 that candidate experience sucks, I had three laptops and I forgot to bring my personal spare to the interview.

In general the core problem is there is zero incentive for hiring managers to do anything but shotgun candidate pools like they do today. There’s also no feedback loop to evaluators to help them improve. False negatives are completely tolerated despite there being a huge gap between CS jobs demand and CS graduate supply.