[mytailorisrich]

Well, I think this is the difference between the official positions (which are the same on both sides) and the reality on the ground in terms of relative power.

The PRC/mainland is massively bigger and more powerful than the ROC/Taiwan so they think that they have the means to pursue their official position.

Taiwan knows that they don't have the means to pursue their official position so there is little point making noise about it. And furthermore, the "3rd faction", which the current President belongs to, is not sympathetic to that position, anyway. But when the KMT is in power they do at in way that protects that position (eventual (re-)unifaction).