If the original tax rate is restored, the market could be immediately suffocated. But if the preference is extended, people will suffer from the false impression that "whatever the government gives, it can never take away."
土增稅減半優惠到期後，如果回復原先的高稅率，可以想見市場立刻變回一灘死水；但如果繼續延長優惠，又讓人有「政府放出甜頭就不可能收回去」的錯誤期待。