Pre-K has both student and parent handbooks with very clear cut discipline policies.
Typically the same one that your public school system follows. It is given in hard copy to parents upon enrollment, one signed and returned, one you kept.
It outlines the schools responsibilities, your child's responsibilities and your responsibilities. It is available to print online as well, at any time. It is part of the federal funding.
Your child having to be carried out of the classroom, in full tantrum, at that age is alarming. Making excuses for your child becoming violent with an adult is inexcusable. It is assault on a teacher.
This sort of situation is why police are in the schools, now.
It isn't good. It teaches kids that it is them against the teachers/police. It sets them up for a life of violence and crime. How will kids get an education if nobody is willing to teach them.
How will they have fulfilling careers and earning potential without an education?
Teachers have civil rights, too.
Yes, your child is only 5. NOW is the time to rein it in HARD, while you still can. One the shock wears off, It will look so different.