It was always pushed at the top-level down. Owners of capital wanted cheaper labor so they could profit. The more you increase your labor supply the cheaper the price of labor. The cheaper your labor, the more capital profits. Business leaders and thus politicians and their friends pushed for immigration specifically for this reason. They used indoctrination in the schools to try to force the public to accept it and schools also benefited from immigration but schools weren't the primary driver of it. Schools are a tool of the elite to shape the public in the manner they want rather than the institution that shapes the elite's decisions.

It was always pushed at the top-level down. Owners of capital wanted cheaper labor so they could profit. The more you increase your labor supply the cheaper the price of labor. The cheaper your labor, the more capital profits. Business leaders and thus politicians and their friends pushed for immigration specifically for this reason. They used indoctrination in the schools to try to force the public to accept it and schools also benefited from immigration but schools weren't the primary driver of it. Schools are a tool of the elite to shape the public in the manner they want rather than the institution that shapes the elite.