Yes this is a BIG security hole. I noticed it years ago. There are many ways that international passengers can bring contraband without having to go through immigration and customs. Heck even human trafficking can take place this way. It's amazing that no one thought this out fully.

Most of the time they don't even read your BP at the destination. Just quickly show them the "D" mark and walk out. It doesn't even have to be in your name.

One of these news channels in India should do an investigative piece where they send people who exchange BPs etc. That may be the only way to get this hole closed.