There is a simple way to prevent unions from gaining a foothold in your company: stop treating your employees like crap. Stop implementing life-sapping schedules that prevent workers from having meaningful relationships, give them solid healthcare that they don't want to trade away, give them a paycheck that allows them to live within a decent distance of their work, and don't treat them like meatbags whose sole purpose is to make you more money. If they still want to unionize after that? Fine, throw 'em to the wolves. But quite frankly, reading through the description of what the bus drivers get, the company had this coming.
That said, fuck the unions as well. No, a bus driver isn't the same thing as a programmer. Stop pandering to your audience and do something useful instead.