Wait a minute, don't mix night flying with midnight flying.... maybe the extra penalty charge has to do with noise abatement.
You can do a lot of fantastic flights in the dark before 11 PM, I wish we had such airfield. But our airfielsd strictly align their closing times to sunset, and charge extra for keeping open beyond that, and even separately surcharge for switching on the lights for you....
Anyway, night flying in a single engine plane is about 2.5 times more dangerous than day flying, mostly because of the inability to make emergency landings in the dark, and the higher risk of spatial disorientation. So don't get too fond of it. I love it - but at the same time, I rather fly within sunset + 1 hour, not later.