Some states offer scholarships and grants that are only for their in-state kids to go to their in-state schools.
As a side note, does this only really pertain to the mid/upper level recruits and not the elite recruits? It seems the direction that things are going is that the NIL for elite athletes is in some ways replacing the traditional scholarship route. Donors who are giving large amounts to a program probably aren't going to be too concerned about dropping 10k for kid to get the rest of the tuition paid for. Obviously, another example of the more money and donors a program has, the more kids they can grab up.