You would be wrong. there are a shit ton of trucking companies that operate 10 - 20 trucks. Owner operators which is probably what you are thinking of is only about 9%. I admit I had to look for some solid data but working in the industry I felt like you were wrong on your assumptions. IDK how accurate this info is but here is some for you. For the sake of argument lets say 9% is accurate and the 2M number is accurate. So lets say 180K trucks park all the same week... You will feel it. But they tried this in the 70's. Too many people don't do it so it becomes a blip not a wave.
Trucking Statistics | TruckInfo.net
How many trucking companies are there in the U.S.?
Estimates of 1.2 million companies in the U.S. Of that figure 97% operate 20 or fewer while 90% operate 6 or fewer trucks.
How many trucks operate in the U.S.?
Estimates of 15.5 million trucks operate in the U.S.. Of this figure 2 million are tractor trailers.