Does anyone know for sure that when students are refunded, teachers will lose their money?
But, whether the teachers lose their money directly or not, it will basically mean that trial lessons will become almost "free" i.e. no income for teachers. The higher the price of the trial lesson the more students might become tempted to claim their money back exactly on that expensive" lessons.
Also, IMHO, trial lessons should be priced with the final price of a regular lesson in mind. If e.g. your regular lesson is at 30 USD per hour, a trial lesson at 5 USD will attract many curious students who finally will not book a regular lesson because they find it too expensive or just can't afford it. This also will have a negative effect on the lessons-per-student ratio of the teacher which is one important criterion for selecting a certain teacher. So we might end up in a vicious circle.