In my personal experience this is partially true, although I now work for a big public company and there's a lot of that stuff in my particular department. Some of it is judge institutional culture or management style.
The pot luck lunch is definitely a government thing, but there are particular reasons for it. At least in the agency I worked for, there was no budget for entertainment or morale lunches or whatever. Way more time than was really necessary was always devoted to whether, say, the holiday party should be at a restaurant or be a pot luck in the office conference room. The issue being that if it was held at a restaurant everyone was going to pay for their own meal, and then there are concerns that if you go to a nicer place you might start pricing out the low-paid admin staff, blah blah ...)
So Mrs. Piob's first Xmas this last December. I ask her if she's getting off early on Xmas Eve. She says the brass has made a point everyone works until normal time as they don't want to be seen wasting tax payer dollars. Of course, the Friday before was the Xmas party, and several staff billed out their morning ours to "overhead" so they could set up for the Xmas pot luck.