In fact, I have seen disclaimers on some packaging indicating that they are not to be sold to minors. Any Die Cast an adult collector buys. No, they are not toys. The fact that they can be found in the toy aisle is not significant. They are located in this area as a result of marketing decisions by those that are not enlightend.
Several manufacturers offer banks.
There are both clear and black window versions of these cars. Historically, banks had blacked out windows. These became highly desireable, since at the time, the regular cars had poor interiors, and the banks were actually better looking. Over time, Die Cast car interiors became better, and banks became less popular. To keep banks going, manufacturers gave banks clear windows as well - and slashed production to only a few units.