Actually, "non-essential services" are the things we pay for that the WH is using to screw us (yet again) by denying us access, while maintaining their cushy lifestyles in the WH, Congress, Judicial branch, et al.
I just read a story on Foxnews about a group of Honor Flight vets and their companions pushed through a closed gate and visited the WW2 Memorial. They were aided and abetted by a handful of congressmen, and to their credit, the Park Po-Po did nothing to stop them.