Even more fun fact.  These public schools that take in transfers are always the same few schools.  MNW, Central, Venice, and few newcomers like Booker and West Boca etc.  There are wayyyyy more public schools than those few that you are referring to.

But what they do is to enforce strict recruiting and transfer rules.  The only want fair play.

There is no published data that compares how many transfers go to public vs. private high schools in Alabama.  But the AHSAA explicitly cited eligibility disputes tied to transfers into private schools as a reason for restructuring their classification and playoff system. But to your point, it is true that public schools receive more transfers than private schools in states where data is readily available on the destination of transfers, such as Texas, California, Georgia, and, yes, Florida.  The data and empirical observation also support the view that private schools receive a higher percentage of high impact/top-tier/elite transfer talent.     

Fun fact. Public school accumulate and stockpile much more football transfers than privates do on average. 

No, but it appears that they aim for "like vs. like".  And that looks different in different states, depending on demographics, school/transfer policies, etc.  So I applaud those involved with the SSAA for providing a competitive opportunity for like-minded schools.