Different people have different priorities. Sure, pay and benefits is a factor that just about everyone considers. The difference lies in the weight that factor holds for them compared to other factors such as a genuine enjoyment from their work, wishing to avoid taking from the strike fund, or any other factor that matters to them.
For most people, the consideration works out in favor of a strike. In a large enough population, though, it won’t for some people. 95%+ is really good. Let’s take it and not alienate those that didn’t vote for it. That leads to attrition of the union.