Of course, people can and do jaywalk all the time. I'm told it's different in some places but I am pretty sure that someone actually getting issued a ticket for jaywalking in Boston or NYC would practically be a newsworthy event. In actual life, (most) people do behave sensibly. Pedestrians cross empty streets at will and drivers mostly don't run over people who cross in the middle of traffic.

Whether you like it or not, there are cars in most areas of cities and pedestrians (and cyclists) mostly interact with them without too much carnage, in part because there are rules that most people follow most of the time.