Well, we've not had a king for several decades, so that partly explains it
And whilst I'm not going to excuse away some of the more ridiculous behaviour at present we shouldn't pretend people just behaved themselves through two world wars. Rationing had to be brought in in WWI partly because people were deliberately and selfishly buying up food (panic buying), leaving some fellow citizens without enough to eat. And the government was required to make certain actions punishable with fines, etc. because people could not necessarily be trusted to do the right thing.
As I say, I'm not excusing modern selfishness and myopia. We just shouldn't look at our history with rose-tinted glasses either. Some people have always been arseholes.
At present, if you want a wartime analogy (and we're British, so what other analogy would we use?) Germany has invaded Poland, Chamberlain has declared war but we are in that 'Phoney War' period before it all properly kicked off on the Western Front. Behaviour may change if/when we reach the May 1940 stage of the virus in this country.