One big thing worthy of note is the psychological aspect of all this. We can’t simply boil everything down to living conditions and policies when culture is also an important element.
East Germany lived under a police state for decades. This does not promote trust or pro-social behaviors in a populace, it promotes the keep-your-head-down-and-obey mentality that authoritarians benefit from. This mentality can then be handed down parent to child in families.
This cultural difference could potentially be a big component.
When people become accustomed to and expect hardship, abuse and distrust, it’s not so easy to win their support with positive action. They won’t trust it, they’ll just be waiting for the other shoe to drop. They believe in an authoritarian world, ruled by hierarchy and power, and nothing else really makes sense to them.
I’d be curious to see research going into a variety of cultural and public health differences between the two former halves of Germany, to see if my idea pans out.