When you live in the Chicagoland area you are in a residential zone for community college. It shows up on my property tax bill each year. So most kids live within a short distance to community college. Not all but most. So if you have access to car you can live at home and go to community college. It is quite common for many of the kids that go to our HS. I didn’t look at the costs of the local community college but I think it is around $5-6K a year for tuition/fees. So doable for many people.
That being said without merit you are not going to get a COA(including R&B) under $20K a year in IL. In most cases it will be higher even at the directional schools. Merit will bring the costs down to a reasonable number for some kids. But UIUC doesn’t give much merit as it doesn’t have to. Hence, the reason IL has one of the largest rates of high stats kids leaving the state for college.
Overall it isn’t surprising that people are trying to cheat the system. People do it on taxes so why not try on college costs.