In-State Tuition in Multiple States

This student’s parents split their time between two states – find out whether he can get in-state tuition in both: https://www.collegeconfidential.com/articles/can-i-have-in-state-status-in-two-states/

I know a situation like that—Virginia and Texas. Kids got in state tuition in both. A parent with residence in each state

A lot of kids go to school in states that are not their own. Boarding school—parent moves, kid stays with friends family. If you can fill out the instate forms, and they do vary by college, if you can pass muster on them, you can get that instate tuition. The key thing is having a parent that has residence in that state

Don’t colleges know that some students are doing this? Do they just not care?

Colleges typically consider a student under a certain age (age 24 in California) to be a dependent of their parents. Therefore it is the state residence of the parents (not the student) which typically matters for in-state tuition.
In regards to “do the schools know that students are doing this” I don’t see how the schools would care. If I moved to a different state from my partner then I’d be paying that states taxes (property tax, sales tax, gas taxes, income taxes) for the majority of days in each year. The parent is either a resident of the school’s state or they are not.
As a California resident (highest taxes in the world) there would be several advantages if either my spouse or I became a resident of a different state (converted a job to fully remote and moved residences to another state). However, our incomes are generated in CA so CA will tax us anyway.
We have a family friend (11th grade) whose parents are divorced and live in separate states. She is solely a dependent of her father and has very little contact with her mother in the other state. So in that case I doubt she would get in state tuition to both states, but I don’t think that is right.

There is also state reciprocity. I live in MD, and has reciprocity for in-state-tuition with VA, SC, FL, and if I am not wrong, also with TX and GA. Not for all majors, though.