Why Changi Airport has different security procedure?

Since 1 August 2007, Changi Airport has different  security procedure for its visitor, when you're coming from Australia or the US. The Changi Airport Authoritative will apply certain condition that will be applicable. Here is the difference.

a. Australia or the US
The restrictions apply to flights to and from Australia and the US.
Passengers are only allowed to carry liquids, gels and/or aerosols in containers of 100 ml (3.4 ounce) or less in their hand-carried luggage. These containers must be packed in one transparent, re-sealable plastic bag of not more than 1 litre (quart-size) in capacity. Passengers should check-in liquids, gels and/or aerosols beyond the quantity allowed.

b. Air India, Air India Express, Northwest Airlines or United Airlines
The restrictions apply to all flights on Air India, Air India Express, Northwest Airlines and United Airlines.

Passengers are only allowed to carry liquids, gels and/or aerosols in containers of 100 ml (3.4 ounce) or less in their hand-carried luggage. These containers must be packed in one transparent, re-sealable plastic bag of not more than 1 litre (quart-size) in capacity. Passengers should check-in liquids, gels and/or aerosols beyond the quantity allowed.

c. Canada, China, Dubai, European Union1 Member States, Hong Kong, Indonesia, Japan, Macau, Malaysia, Maldives, Mauritius, New Zealand, Norway, Philippines, Qatar, South Africa, South Korea, Switzerland, Taiwan, Thailand or Vietnam

The restrictions apply to flights departing from the above mentioned destinations.
Passengers are only allowed to carry liquids, gels and/or aerosols in containers of 100 ml (3.4 ounce) or less in their hand-carried luggage. These containers must be packed in one transparent, re-sealable plastic bag of not more than 1 litre (quart-size) in capacity. Passengers should check-in liquids, gels and/or aerosols beyond the quantity allowed.

d. India
The restrictions apply to flights departing from India.
Passengers are not allowed to carry any liquids, gels and/or aerosols in their hand-carried luggage. Passengers travelling on these flights should check-in all liquids, gels and/or aerosols in their checked-in baggage.

Note : 1 European Union Member States include Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and the United Kingdom.
Changi Airport Security Procedure
 

Why this could be happen?
Since 2005, an upgrade in screening technology and rising security concerns led to all luggage-screening processes to be conducted behind closed-doors. Plans are also in place to install over 400 cameras around the airport to monitor passenger activity around the clock and to check on suspicious parcels and activity to discourage bomb attacks similar to the 2005 Songkhla bombings in Southern Thailand where Hat Yai International Airport was targeted. Tenders to incorporate such a system was called in late September 2005.

Since the September 11, 2001 attacks, and the naming of Changi Airport as a terrorism target by the Jemaah Islamiyah, the airport's security has been stepped up. Roving patrol teams comprising of two soldiers and a police officer armed with machine guns patrol the terminals at random.

Source: Wikipedia

Do you agree with certain airport security procedures?