[nickff]

Some unions can neglect certain locals, especially if the local is small and distinct from the union's 'main area'.

For example, if a group of retail employees forms a new local for a large office worker union, the large union may not put much effort or many resources into achieving a 'good agreement' for the retail employees (because it's not worth the prospective increase in dues). Then, the 'good employees' will leave out of frustration, and only 'bad apples' remain, until the retailer shutters the store for under-performance.