Pay raises, more time off, better benefits. A newly hired employee has very little to lose by supporting unionization.
>And why, if organizers are lying, can't Amazon just disprove them by showing to the public their perfect working conditions?
Because when Amazon shows good conditions, everyone says that it's a manufactured scenario or just an anecdote.
>Finally, isn't it a natural instinct to side with the weaker element in a fight?
Which is precisely what organizers want to exploit with publicity that could very easily be taking things out of context. A union organizer has almost nothing to lose by massively exaggerating.
>Does Amazon really need your support, or are the workers one paycheck away from homelessness in need of it?
Depends on whether or not you care about being manipulated into supporting something that could be a lie. It's not even "support" of Amazon, it's just questioning of the accounting of one side of a debate.