What is the ruling on the work of a driver whose school principal compels him to pay a percentage of his wages to continue working, and what is the ruling on the principal's action?

If the selection of drivers and buses for student transportation is part of the school principal's job, then it is impermissible for him to ask for money from the driver, and it is impermissible for the driver to pay it, because work-related gifts are haram (forbidden) and considered ghulul (ill-gotten gains). However, if the driver fears injustice should he not pay, then he may be excused for paying, and the sin would be on the principal.