What is wrong with queue-ing up?

I cannot understand why people cannot tolerate others who were splitting into two groups for standing in two lines when THEY ARE DOING THE SAME SHIT?
It happened in our lovely Tesco, the one and only entertainment for UTAR-ians and fellow couples to date around (takde shopping centre ma, paktor sana la)

Me, A, B and B's family opted for lining up in two lines on a busy shopping day. It's the average weekend in your favourite supermarket when you wished you had the Touch n Go card to relinquish the ever extensive cashier line. Me and A in this line, and B and her family stand on our side. After the long awaited movement of the line happened, me and A ushered B to come over to our side. When they pushed their trolly over (all our stuffs are there, i was merely holding a couple on my hand), here comes the common dramma in the midst of the havoc.

The varsity juveniles behind us started to give us stares and bitchy whispers when they saw B coming over. What is the big deal when they are doing the same? Ethically, we have the rights to do so unless we had two trollies full and that would be disrespectful. Otherwise, with only a meagre amount of items in tow, we are just customers believing we got ourself the best option between the two we had. Not only they are mentally challenged to even state how unfair it is, they thought their Penang dialect that means "mereka tak tau dengar" are threatening.

The only thing we had to say is "yala, we don't understand maaaaaaaaaaaaaaaaa"