Every employer must pay all wages earned by an employee at least once every 31 days on a regular payday designated in advance by the employer regardless of whether the employee requests payment at longer intervals. Unless paid earlier, the wages earned during the first half of the first 31-day pay period become due on the first regular payday following the first day of work. If wages earned are not paid, the commissioner of labor and industry or the commissioner's representative may demand payment on behalf of an employee. If payment is not made within ten days of demand, the commissioner may charge and collect the wages earned and a penalty in the amount of the employee's average daily earnings at the rate agreed upon in the contract of employment, not exceeding 15 days in all, for each day beyond the ten-day limit following the demand. Money collected by the commissioner must be paid to the employee concerned. This section does not prevent an employee from prosecuting a claim for wages. This section does not prevent a school district, other public school entity, or other school, as defined under section 120A.22, from paying any wages earned by its employees during a school year on regular paydays in the manner provided by an applicable contract or collective bargaining agreement, or a personnel policy adopted by the governing board. For purposes of this section, "employee" includes a person who performs agricultural labor as defined in section 181.85, subdivision 2. For purposes of this section, wages are earned on the day an employee works.