If one employee negotiates with an employer, the employer holds all the cards. Standing together to negotiate with an employer makes us stronger. This is why we have a collective agreement: collective means we came together to create quality education and a decent workplace.
Every bargaining year, each college holds a demand set meeting where employees suggest what they want to bargain for. These are voted on and sent to the elected bargaining committee. The union is thus not an outside player doing something for employees. The union is the employees, a mechanism for concerns to be addressed. Bargaining, leading to a collective agreement, is the strongest manifestation of our collective will.
Your collective agreement is an incredibly detailed document. Managers and employees must, legally, follow what they have agreed to. The document moves us away from favouritism, sweetheart deals and random management choices towards fairness and transparency.