I tried to keep it short and I began to write an entire monograph lmao.
TLDR: It just isn’t as materially important.
People can easily travel between the two states, there’s iirc hundreds of thousands that pass through the immigration bridge weekly.
Families are not separated and both states maintain cordial relations.
Personally I would obviously like to see it happening, but when it isn’t necessary, you get limited by political bureaucracy than anything else.