I see this all the time. There is a line at the SP carpet and at the last minute, people swarm in from all sides and seingly blend themselves in, though they are actually breaking the line- and they call you rude for not allowing them to break the line.
If they don't have bags, i let them pass, if they have the house and farm, they don't get in front of me.
Not being rude, just maintaining the integrity of the line.