Earlier quoted context omitted.
The ROC is de jure a country, and the PRC is de jure a country, but mostly not in the same legal systems, and with essentially coextensive de jure territory. De facto mainland China and Taiwan are separate countries, with distinct territories, governed respectively by the PRC and ROC. That is the basis (or perhaps just expansion) of the upthread description that Taiwan is, de facto , a distinct country from China.
So the ROC and PRC are de jure countries, and de facto countries, and well countries. I still don't understand the point of the qualifier. I don't hear people refer to China as a de facto country so why use the qualifier for Taiwan?
Actually, looking back, that was probably not something I should have said.
ROC and the PRC are each (in their own legal systems) the de jure government of the same (widely formally recognized, usually with the PRC formally recognized as the government) country, “China”.
“Taiwan” and “mainland China” are de facto countries, governed in fact by the ROC and PRC, and are often treated as such by countries that formally recognize one China with the PRC as its government.
> why use the qualifier for Taiwan?
Because in most legal systems that aren’t that of the ROC itself, the PRC is the recognized government of the single de jure country of “China” that subsumes both the de facto countries of mainland China and of Taiwan. ROC is, in those systems, only and exclusively the de facto government of the de facto country of Taiwan, and not the de jure government of anything, and Taiwan is de jure a province of China.