Is it normal to leave your doors open while you're home?

There was this documentary where an American director went door-to-door just barging into Canadian families' homes to show that Canadians keep their doors unlocked and how apparently stupid that was. Before I saw this, I thought Americans believed Canadians kept their doors unlocked 24/7, even when on vacation. Though, this IS true for many rural families. Canadians are pretty trusting, and with good reason; our crime rate is WAY lower, but, until I saw this documentary, I believed that Americans kept their doors open when they're home and awake, but this documentary seemed to suggest otherwise. This shocked me as much as the Americans were shocked about the Canadians!

Like somebody in the documentary said, it just seems very odd that someone would lock themselves in their own house! This must only be an American thing. For a few decades now, most Canadians have locked up when they leave, but where I live in Canada, it's considered rude to keep your doors locked while you're home. People who do so are considered very shifty and secretive. People assume they must be hiding something or want to be left alone.

In Canada, friends and neighbours often drop by unannounced. Sure, it can be annoying, but it's customary. The custom is to just barge in and scream "hello!" or "good day!" to announce you're arrival. The host then bellows back "come on in!" in a friendly tone. If a relative or friend were to come over to find your door locked with the cars in the driveway, you could expect an annoyed phone call later. Often, people will just walk around the house trying every door before they leave.

Delivery people here will ring the doorbell or knock, but some still come inside to give you your package or talk; often uninvited. I guess this must all seem like crazy talk to an American, especially an urban one. But, to me, having to unlock the door to leave your own house is crazy! I don't personally know or know of anyone who's ever been robbed while they're still at home in broad daylight! (Though I'm certain it has happened.) If you live in the ghetto, you're exempt from my astonishment.

So, do you think America really is more dangerous and people have actual cause to keep their doors locked, even in suburbs and rural areas? Do you think Canadians are absolutely nuts for ever keeping the door open when anybody could just drive up and walk in? Do you think Americans are too untrusting of their fellow man and overly cautious? is it normal to keep your doors open during waking hours while you're home?