He mentioned an East Asian Institute (EIA)survey. I can't find the survey mentioned by DPM Tharman. The list of publications by EAI is found here. I wanted to check this survey to see if it explicitly links the falling average nominal income in Taiwan to its tight policy on immigration and whether Tharman himself made this link. However, I realise I don't need to do this to debunk DPM Tharman.
"As a result, the nominal income of the average Taiwanese has flattened for more than a decade"
- Minister Tharman
Here is Taiwan's real GDP Growth[Source] since 2000:
Here's Taiwan's per capita GDP:
Taiwan has grown its GDP steadily for the last 10 years. The average per capita GDP (nominal and real) has also grown. The only possible reason why an "average Taiwanese" does not feel richer is the income gap is increasing or there is rising cost of living e.g. housing that does not show up in its inflation numbers. However, the Taiwanese are known for its "growth with equity" [Link] approach and maintained an income gap far lower than that of Singapore's. So what is Minister Tharman talking about? The wages of a large segment of the Singapore population has been stagnant for the past decade and many analysts have found that it is due to the large foreign influx[Stagnant wages, immigration fuel Singapore squeeze].
A country can enhance its competitiveness by keeping its door open to selected foreign talents to complement the skill set of its local workforce - few people will disagree with this. However, this is not what PAP has done with its immigration policy which resulted in a massive influx of foreigners into Singapore. Minister Tharman is wrong about the problem Taiwan faces and prescribes the wrong solution for them to justify PAP\s own flawed policy that has caused so much unhappiness among Singaporeans.