The SSRL website says it best.
FACET, LCLS and SSRL are facilities owned by the U S Department of Energy at SLAC and operated by Stanford University under contract with the DOE. The US invested hundreds of millions of dollars in designing and building SSRL and LCLS, and the annual operating costs are not insignificant. The DOE owns many such “User Facilities” at various DOE labs across the United States. The facilities are made available to Users under standard agreements prescribed by the DOE. Users may use the facilities under one of two sets of conditions – for free, which is the non-proprietary version, or on a “full cost recovery” basis, which is the proprietary agreement. SLAC has very limited flexibility in negotiating the terms and conditions to either of the versions.