For someone who is carrying on a business, there aren't similar limitations. The Income Tax Act generally allows people who are carrying on a business, or requires them, to compute their profits. In doing that, they would be able to deduct reasonable expenses that they incur in the course of carrying on business. There are no limits.
With respect to employees, the Income Tax Act generally doesn't allow employees to deduct amounts that they earn for the purpose of employment, subject to certain specific exceptions. This is one of those specific exceptions where, subject to the limit, the employee is able to deduct that amount.