Because Taiwan was much more prosperous in the last few decades of last century, before Taiwan fully embraced western democracy and started having two ruling parties. Now, however, with Taiwan's economy/average wage being almost stagnant for almost twenty years, and the huge mess in the Taiwan politics, it is hard to see anything good came out of "democracy".

> But why should they have a realistic impression if information is controlled?

They may not know Taiwan well enough, but on average they know it much better than westerners.