WOTC - Slow clearance at checkpoint

I asked this question in the Wisdom of the Crowd:
Why does it take a longer time to clear the Singapore side of the checkpoint for travelers by car?

Here are the responses:
38 % - The Singapore authority deliberately slow down the process
29 % - The computer system is slow
24 % - The Singapore authority is more careful about checking the visitors
10 % - There is a shortage of manpower

See the pie chart at:
http://www.wisdomofthecrowd.sg/chart.aspx?ID=748