Yes - this is covered. They are very specific that you may NOT use the drive-thru on a drive-in shop even if they ask you to.
At the end of the guidelines, "What ifs" are covered:
1. What if I can't order because no one answers and I have waited for 5 minutes? Switch stalls and wait up to 5 minutes again. If still no response, evaluate cleanliness and the POP menu cards and then leave. Enter 99:00 for Q1 and Q2 and answer No to all other questions.
2. What if my order never arrives? Wait 20 minutes then evaluate cleanliness and the POP menu cards and then leave. Answer No to the questions you were not able to evaluate.
3. What if the Drive-In or stalls are closed? Evaluate cleanliness and the POP menu cards. If you are asked to go through the Drive-Thru instead, DON’T. Enter 99:00 for Q1 and Q2 and answer No to the questions you were not able to evaluate.
In 10 years of shopping Sonic, I have had all 3 happen. I followed the guidelines and got paid. A couple of times, instead of following those guidelines, I rescheduled like ceasesmith did. That works fine, too, except then you do have to make another trip.