They also need to get more creative with who they are hiring and what “benefits” they are offfering. A split schedule like that sucks for someone looking for anything more than part time work. If they can come up with benefits that attract say, stay at home parents looking to make some extra money, that particular split in the schedule may not be so bad for them. But they would also likely need other non-traditional side benefits that full time workers in other jobs might not, like the ability to bring younger children (not yet in school) to work with them on their route. A benefit like that might bring in more drivers and not even cost the company anything but too many places are stuck in a traditional workplace mindset.
Starship troopers has a line in it that the crusades were created by population pressure (primarily young men being denied a good chance at a future).