Most Mainland Chinese people still know how to use traditional characters for historical or aesthetic/artistic purposes. There’s a bit of a complex from some Taiwanese and HK elitists who think China is trying to impose simplified on everybody or that people who use simplified are dumb, but there really is no “right” script. Traditional characters definitely look more aesthetically pleasing than their simplified counterparts, but also making it easier for people to gain and maintain literacy is much more important than some notion of tradition.

HK and Macao use traditional characters, sure, but it’s not because they “adopted” the characters that the ROC used. They became foreign colonies during the Qing dynasty, which also used traditional characters, since simplified characters weren’t invented yet. However, they are used to write the cantonese language, not the mandarin language that the ROC used.

Singapore transitioned to using simplified character and now you’ll pretty much only see mandarin written in simplified there. Malaysia is in the process of transitioning, hence it’s more of a mess.

Taiwan still uses traditional out of some sense of national pride

However “traditional” is not the original characters exactly, and some traditional characters are already simplified to some degree

oh wait this is a meme why did i type all this