That's first hand experience, and unless it's challenged with verifiable evidence, I'd be content to consider the author credible. If he's on the ground there, living and working, then his observations are of course valuable - and I don't know how we'd ask him to 'back it up' any more than he has.
I almost answered the same question because I know people that have worked there and heard the stories that they told. I was going to answer that inclusive of the anecdotal bit, but with more links to how the Philippine government preps people to go live and work there, but I didn't have time.
First hand accounts are good. First hand accounts with a little support from things that reinforce what you're saying are great. But I think we should give the benefit of the doubt in cases where people basically say "source: my two eyes, I live and work here."
I can tell you how crowded the buses in Manila tend to be, in great detail. Should I have to take a picture of it too? I don't want to put too much of a barrier in front of folks that have this sort of rare knowledge that might otherwise leave questions unanswered completely.