CSS vs PMS
 

It is observed that many people who do not get allocation in top three or four groups of CSS switch to PMS (if they get allocation there). Why???

Because a lot of people go for the perks and when their expectations aren't met, they switch to different areas.
I don't see any other reason. If there are hurdles in way of service in the "lower tier" groups, then maybe we would have heard about them. People join civil service for the power and privileges, and when those don't appear to materialize even civil service becomes undesirable.
I am not saying if this approach is right or wrong; this is just my opinion.

[QUOTE=Muhammadwd;1111756]Because a lot of people go for the perks and when their expectations aren't met, they switch to different areas.
I don't see any other reason. If there are hurdles in way of service in the "lower tier" groups, then maybe we would have heard about them. People join civil service for the power and privileges, and when those don't appear to materialize even civil service becomes undesirable.
I am not saying if this approach is right or wrong; this is just my opinion.[/QUOTE]
Let us keep privileges aside. In a country like ours one needs adequate power to fulfill one's responsibilities, and to serve, specially the oppressed because their rights are often seized by the powerful.
Recent example is the silence of administration against petrol and pharmaceutical mafia while in the normal routine they are busy cracking down poor vendors.

So, can we assume that the PMS officers are more involved in policy making and implementation than the most of civil service groups.

I got your point of perks and power and I agree with it.

I agree.
However, choosing certain groups over others is something that feels a little pointless unless you have your perception of quality regarding those groups.
The rest is opinions and hearsay.