The basic XL is, you know, basic and it doesn't have lots of things. It's designed to be a fleet truck and fleet trucks don't typically need storage under the rear seat. The XLT trim level only costs about $2,300 more and really should be a lot more comfortable and pleasant to own.
Several videos out there showing the under seat storage in the Ecoboost and Hybrid XL. Only thing is that hybrids have the car battery under the seat, so they have a little less room. Otherwise, the XL has them.