The problem is in the way a lot of people think nowadays.

Current thinking:
"It doesn't look like anyone owns this, it's mine now."

Correct thinking:
"Nobody gave this to me, and I didn't buy it, so it belongs to someone else."

I see this as the continuation of a trend of people not growing up intellectually beyond adolescence. Witness the rise of outrage culture, where people are personally offended that other people may hold different opinions.