In regards to Federal agencies, a lot of it comes down to many people just not knowing much about these agencies, and much of what they do know are the scary bits and pieces capitalists have broadcast through their media (I hesitate to just call them conservatives, as their agenda is completely separate from moving law and government in a slow, conservative manner).
I for one didn't even know we had an agency like USAID, which sounds like it has done wonderful work around the world. Most people (again, myself included), probably don't know just what the DOE's main function is. Turns out it's a pretty hands-off agency, and shutting it down will mostly just harm kids with disabilities. Why we shut these agencies down is beyond me, but I guess it makes them look like they're doing something without going after the actual big fish, like our national "defense" apparatus. Oh no, there we're going to build a "golden dome". A very "efficient" one I'm sure.