Just what, exactly, are those "additional resources" that ALPA has and IBT does not? I'm sure enquiring minds would like to know.
In-house Economics & Financial Analysis department that is so highly regarded that even the airline management teams pay ALPA for the service, dozens of attorneys and professional negotiators, including experts in fields like scope and insurance, professional lobbyists that specialize in pilot issues on Capital Hill, etc.... If you're a trucker and want a union that specializes in your field of work, then you can't beat the IBT. But we aren't truckers. Pilots need representation that specializes in pilot issues.