It is relatively easier to find PhDs in that profession if it is academic qualification you are going after. And it seems that PAP believes in academic qualifications and so does SDP.
Medical doctors and PhDs are very different from each other. The only thing they have in common is the name doctor.
Bill Clinton was a Rhodes Scholar. Barack Obama is not only a PhD, he is also a law professor.
It is true that academic qualifications are not enough to be a good cabinet minister. But the question is not whether academic qualifications or having a heart to care for your people are good enough. At that level, you need both. That is why Zenawi of Ethiopia and SBY of Indonesia went for further studies after they became politicians. When you are at that level, you need to understand politics and economics.
I would even say that academic qualifications wise, the current Singapore cabinet is under-qualified.
Lee Hsien Loong - degree was in mathematics. Only a masters in public administration. General in the army. Does that tell you anything about how a government works? Should have been a lawyer like his dad.
Teo Chee Hean - background in engineering. Former admiral. Not necessarily qualified to lead a government.
Tharman - background in economics and public admin. Good enough qualifications. Not surprisingly, probably knows what he's doing.
Shanmugam - background in law. Good enough qualifications. Although the examples of Tey Hsun Hang and Bill Clinton teach us that a law degree does not teach you how to keep your dick in your pants.
Ng Eng Hen - medical doctor. What the fuck is a medical doctor doing running my education ministry?
Lim Hng Kiang - background in engineering. Also has the EQ of an engineer.
Khaw Boon Wan - another engineer, but less bad EQ than Lim Hng Kiang
Gan Kim Yong - why so many fucking engineers in the cabinet?
Vivian Balakrishnan - why the fuck is a medical doctor running the Youth Olympic games?
Heng Swee Keat - Economics and public Admin, also ran MAS before. Good enough, but Education is a strange portfolio
Yaacob Ibrahim - another engineer
Lui Tuck Yew - Chemistry. Public Admin. Military. YAwn.
Lim Swee Say - Engineering
Iswaran - Economics and Public Admin
Chan Chun Sing - Economics and military. Maybe that's why he actually knows something.
Grace Fu - Accountancy. EQ of an accountant.
Engineering is not totally a bad degree, but the bias is towards making Singapore very corporatist. Glaring admissions from the cabinet: none of them were former businessmen. No degrees in political science, although public admin tells you something. Medical doctors - pretty irrelevant, although 1 or 2 in the cabinet is OK. Not enough lawyers. All have degrees from UK / USA / Australia. Maybe not enough diversity. No professors from academia. Nobody from the media (that's why they're so clueless politically) Way too many engineers.
Over the years they've hoodwinked you into thinking that good academic qualifications are good enough. What field those academic qualifications are in is equally important. Then you have people with good degrees but irrelevant ones. Vincent Wijeysingha is a PhD in sociology, which could tell you why he's an expert in migrant workers. Note that Chee Soon Juan's degree is in neurology, and that could tell you why he has the EQ of a scientist.