The primary difference is in the medical. In the UK for a NPPL one does not need to visit an aviation medical examiner. The medical is the same as for a taxi driver,bus driver etc.A GP can sign you off.Different medical regulations.
That is only possible in the UK because all medical data is centralised (so I haved read). Other countries, have such strict privacy laws and a doctor gets only the info the patient gives him.... often not enough for flying. But that's a whole different subject.
Communities, cities, etc. have no funds to pay for or maintain airfields. Those that do own fields try to sell them, or turn them into more profitable industrial parks
Turn over the airfields to the city and you can expect it to be closed completely within a very short time!
Most fields offer reduced landing fees for students, at least during the week (because of noise issues often not on the weekends).
As you see, there is a lot more involved here then simply saying get rid of landing fees!
Mowing the grass can be expensive depending on who does it. Many glider fields have a local farmer do it because he can keep the grass for his farm animals, so no cost. But that means he wants it to grow higher then is safe for flying, which can mean a whole lovely weekend on the ground! Others fields get mowed by club members, others have to hire someone.