The reason for the 'anal' behaviour during international transit is some bad experiences of the immigration authorities of people misusing the system. Back in the day when DC10/B747/etc had limited range it was 'normal' for longhaul aircraft flying between SE Asia and Europe to make a stop in CCU/DEL/BOM and all pax deplaning directly into the concourse.

The GoI want AI to develop BOM/DEL into a hub and allow for quick connections. Clean security arrivals are usually reciprocal so India expects the EU & US to recognize the CISF security procedures as equivalent....