Are school and university regulations, such as disciplinary actions for misconduct (warnings, suspensions, expulsions) and the prohibition of striking students, contrary to Sharia, especially given that some offenders, such as alcohol drinkers, are expelled without being punished according to Sharia?

These systems, regulations, and bylaws were established to consider the welfare and repel corruption. The mentioned punishments fall under the category of ta'zir (discretionary punishment), which is permissible. As for the punishment for drinking alcohol, it is one of the prescribed punishments (hudud) that the ruler is responsible for implementing.