knows from the stats that chances of each are a couple of percent (so doesn't invest too much for her sanity) and is not very enthused by most
How does that manifest at interview? Is she turning up looking reluctant and half-hearted? Making a token effort at tasks or questions?
Or attending interviews without knowing anything about the company or the role she's applied for?
As a minimum she should know what the company says about itself on its website, how it's positioned (and positions itself) in the market, what its values and objectives are, how the role she's applied for fits into the business and where the role would take her. As well as how that all aligns with her skills, experience, goals and values.
She should be taking that information into account in her answers (not just reciting it) and should be able to tell a persuasive story about why she wants to work for this company in this role.
If she can't do that at first stage interviews, why would they want to invest more time going through later interview stages with her? It's really time consuming on the employer side, so if you've got candidates who aren't doing the above then it's a waste of time to take them forward.
It would also damage her credibility if she turned up to first stage disinterested and only started to pretend to be interested at final stage. It makes her look insincere and untrustworthy, which is not a good start to a potential employment relationship.
If she doesn't invest properly at first stage then she shouldn't be surprised that the return on her investment is also low.