The amount of expected personal space in India is significantly less than in the US. Flying from Pune to Nagpur we had to wait in a number of queues. Airport check in, security, boarding. Each time I would stand in line and give what seemed like enough personal space between me and the person in front of me. Without fail someone would come and stand between us. Just cut right in line.
Standing in security people are busy taking out laptops and mobile phones. It's mad max fighting for bins and if there's any opening someone will take it. No particular line.
I was waiting to board my flight and I finally learned my lesson. I was very close to the next person. My colleague behind me left enough personal space and sure enough two people slid in between us. One large man who wanted to get so close he kept bumping in back of me. I put in my patience. I knew it was only going to last a few minutes as we boarded.
Then "buuurp" this deep burp in my right ear from the big man so very close.