Making more $$ for the company is probably part of it.. Most likely it's because Saturday is their slowest day so that's when they want to give the free time away (some weekend rates also have a Sat night requirement, so they could just be aligning them). Also, requiring a Saturday stay might be easier than writing a book of complicated terms to ensure you don't rent for a Thurs/Fri or Sun/Mon work trip, when their rates are higher.


A lot of policies fall into this category. Like why do airlines charge $200 for you to make a flight change 2 months in advance? It doesn't cost the airline anything (it's typically done online and no agent time is necessary) and still allows them plenty of time to sell your old seat.