According to the Philippine embassy website "The Bureau of Immigration in the Philippines inspects all international-bound passengers. This is in line with the Bureau’s mandate under the Anti-Human Trafficking Law of 2003 (R.A. 9233) and the Amended Migrant Workers’ Act of 2004 (R.A. 10022), to stop human trafficking and illegal recruitment."
Personally I don't think this rule or law is very convenient. What the PH immigration does is randomly selects individual interrogate / interview them the purpose of their visit to Singapore, would ask the tourist if they are currently working in some company in the PH, how long would they stay in SG, if they are planning to go back home after few days, etc etc. If they feel you are an eligible tourist, they will allow you to else, you go back home. My sister in law during her first visit here almost didnt make it to the plane. It was her worst experience in traveling.
Until we knew about the Invitation Letter that can be requested from the Philippine Embassy. Still being primitive in a high technology country, the Philippine Embassy doesn't have an option to request this online. You really have to personally go to Nasim Road and process this yourself. What worst is you can't get this right away, you will be ask to go back after a few days when it is ready. Spell hassle. The Philippines has never failed on this part since.
At the airport’s immigration counter, a Filipino tourist bound for Singapore may be asked by the immigration officer to produce an “invitation letter”. This refers to a letter made by a Filipino based in Singapore, inviting a Filipino relative (the passenger) to Singapore for a visit. The inviting Filipino and the invited Filipino must be relatives up the fourth degree of consanguinity (his/her immediate relatives, up to first cousins) or affinity (which is by marriage, up to the first cousins of the spouse). http://www.philippine-embassy.org.sg/consular/invitation-letter/
And this costs around $45. Spell business. Worst, profiting from their own Citizens.
So with the limitation of the invitation letter, we cannot process this for our friend. She's booked to stay for 9 days, planning to stay 3 nights in a hotel and the remaining days in our house but I'm not sure what's the plan now.
Good luck, Marie.