Dairy Queen — slow service in a long line

We tried again going to this dairy queen after trying it a few weeks ago. Again we waited in line for over 30 mins then with 9 cars behind us I gave the cashier my debit card and low and behold had to show my drivers license and sign for this $5.11 purchase. Number 1 is this store in the dark ages? Everyone uses a debit card and the purchase is approved or disapproved so why is it necessary to take the time for a signature? I asked the cashier why it was necessary for a signature when you can go to a grocery store and never sign for your purchase unless its over $50 she was very non-customer friendly... No wonder the wait is so long everyone working there was running in circles and not accomplishing getting peoples orders. Very poorly managed!!!
We have used the dairy queen in omaha and never have had to sign after using our debit card?