Hi Ronen!
To answer you question: Scholastica does not transfer money to law reviews because they decide to use Scholastica for their submissions.
When a law review decides to use Scholastica for their submissions, they do it because they receive an integrated review system at no cost to the journal that allows them to accept submissions, manage the review process, track publication offers, centralize file versions, and (optionally) publish open access content to the web. This is a direct benefit to journals, most of which lack budgets to purchase manuscript submission software.
For more information on how Scholastica benefits law journals, you can check out this blog post: 6 Specific Ways Scholastica Helps Legal Scholarship.
All of that said, could you say more about why accepting money would lead to unfairness? Many journals outside of law reviews charge submission fees as a source of revenue, and there doesn't seem to be a sense in the academic community that these submission fees hurt the review quality or lead to any unfair practices (you can read an interesting discussion on submission fees here. It seems like even when no submission fees are charged, if a journal does not "seriously consider the paper" then that is a problem, and adding a submission fee as revenue for the journal would not make such consideration more or less fair. In fact, additional revenue might allow a journal to allocate additional resources towards improving their review process. Thoughts?