In an ideal scenario, Unions and Shareholders would cooperate to achieve suitable outcomes for both parties; in reality, the amount of power needed to even get a Union off the ground and keep it sustained against the onslaught of Capital means those who wield said power are inclined to use it often. It’s why the (debatably) smarter gamble has been more workers forming anti-Capital institutions: cooperatives, union-first enterprises, sustainable corporations with stringent, anti-Capital bylaws. By removing Capital’s power early, those who do come to the table are more likely to negotiate in good faith rather than scorched-earth tactics.
Don’t slight unions as a whole just because power dynamics in a Capitalist society dictate everything be a zero-sum game. Instead, focus on building a better game and fairer set of rules, and recognize Unions are part of that.