It could be, or maybe whoever loads the luggage into the compartments was looking to make a little extra money, and after cutting in the driver and whomever else needed greasing, went ahead with the plan. I’d guess if they checked records of the people riding like that, they’d find interesting things in any event though.
Back in the 1980s....I was stationed in Germany and did these long-distance tours to Spain and Italy. We had a driver pull up once...who was going to share driving duties with another guy and make a straight run to the south coast of Spain.
He showed me this rigged up sleeping bunk underneath...where the spare driver was always sleeping. It was fixed up, had a fan pumping in fresh air...refrigerator...and a nice mattress. I thought it was a swell idea myself. Guess that would be illegal here in the US.