Yes you are right. My parents always left the backdoor open even when the house was unattended. No one came in. Now you have padlocks and a siren and more busy court-houses than you can shake a stick at.

A copyright notice might say "don't touch" and it might be a step in the right direction but it's a very weak step IMO. Better to not upload your valued work in the first place.

It's a well know fact that the people most likely to call "foul" are those who are least likely to have anything totally original to their name anyway. It's a joke.

"Please don't touch my pictures" Well, Who would want to if they are not up to scaratch. That's the question I always ask. All the best images, the originals, are usually distributed "explicitly free"