[BW2221]

My guess is that the buses are chartered from a privately-owned company that contracts with school districts to transport students.

If you look, there's no name on the front or back of the buses. Usually it says, Naperville, Wheaton, Aurora, etc. on buses owned by a school board.

[RegulatorCountry]

Here, there would only be a number on the back, nothing on the front other than "school bus." The name of the school district would be on either side, and the number would be repeated. Does Illinois have permanent license tags on vehicles owned by government? I have to admit, I've never heard of school transportation being farmed out to a private contractor. Those are Thomas Built buses, built not ten miles from where I am sitting.