Indian airports IME, (BLR and DEL), do not allow anyone but pax, personal security meeting arriving pax, and employees in the landside areas of terminal buildings. Indeed, arriving on a domestic flight from BLR to DEL, pax could not even enter the gate area; the jetway led directly to the concourse exit as would be case when arriving at an Indian, Canadian, or American terminal from an international flight ... if this is generally the case, then it means domestic connections in India must be awful. Fortunately the country is geographically small enough that point to point flights between all the major cities are possible. Another quirk of Indian airport security is that if you are arriving at an airport, you cannot meet anyone departing from the same airport; there is a security check point between arrivals and departures, something I've learned the hard way. When this happened, I told my friend I'd walk out of the lobby and meet him outside, but was told that the guards staffing the lobby would not permit this. Apparently once you have an itin, you have to take the flight, and I suppose if it is canceled, you are escorted to the arrivals area and then you go to the exit. I imagine the logic is that someone who enters the lobby to drop off a bomb will then be forced to suffer the consequences.

Whereas every US domestic and international terminal allows one into the landside areas, except for international baggage claim.

I was surprised to read the Chennai airport allowed non-pax in, but not surprised they charged a fee.

The reason India does this is security. Indians understand that if a terrorist wants to do major damage, it is easier to blow up a check in lobby than a plane, and the body count per dollar is higher. Of course terrorists could get an even higher body count per dollar by blowing up a shopping mall, but the entrances to most of those have metal detector set ups and carry on xrays. The airport lobbies don't have WTMDs and carry on X-rays yet, but I'm sure it is coming.