It wasn't unusual for chartered business jets to have only one set of approach plates to share with both pilots.
It wasn't just about being cheap and not paying for an extra set. A set of Jepps for the entire USA takes up about seven or eight fully packed volumes. Add to that your nearby countries...Canada, Latin America, Caribbean and regs. Now you're looking at a pretty huge collection of charts to carry around all day in a small jet with limited space. Then think about all the updates!
Most companies now use EFBs anyway and are required to have two.