If the unions are a good thing then why isn't everything unionized like food workers, sales people, cash registers clerks, bank tellers and more I could go to. At the least then the UAW should unionize the foreign companies that are building cars in the states. Why is it that only 50% of the Disney workers are members, if the union is that good of a thing why isn't everyone a member and forced to pay their dues?
I guess you could say that if unions are a bad thing then why is anyone unionized? [And by the way, lots of food workers and cashiers (primarily at grocery stores) are union.]
The reasons that not everyone is in unions are complex. They include the fact that labor activists have been successful in getting laws passed for safer workplaces, minimum wages, living wages, overtime pay, family medical leave, workplace accomodation for the disabled, equal employment opportunity, etc. that protect all workers even if they don't belong to the union. We no longer have textile workers in New York locked in their workplaces so that when a fire happens they jump out of buildings to their deaths trying to escape, or mine workers being beaten up or shot by company thugs (okay, maybe we do, but not on the scale or as openly as once occurred).
Also the fact that some management work hard to keep their workers happy so they don't vote to become unionized--that is apparently the fact with Honda USA--it ain't because the UAW hasn't tried to organize those plants (and I think at least one North American Honda plant, in Ontario, is unionized). And no doubt the threat of union organizing leads some management to treat their employees better than they otherwise would.
As for the WDW employees, I'm sure that a large reason that only half are unionized is that FL is a right-to-work state, so there is a free rider problem. Add to that the fact that you're dealing with largely low-paying jobs with a lot of turnover, and a workforce which includes at lot of seasonal employees, retirees, students, etc. that aren't relying on these jobs to feed families, and it becomes even more difficult to organize.