Unfortunately the reason for current fear against helping people violates the 20 year rule, but you wouldn't know that if you don't know where it's from. So I have to remove your question as it's presently worded, but then I'll still give you an answer.

In 2006 there was a highly publicised case of someone getting hurt and then being helped by a stranger who had nothing to do with the original injury. It was highly publicised because shortly after, they then turned around and blamed the person who helped her, took him to court, and he ended up serving time. This got a lot of attention and convinced many that it wasn't worth the trouble, and that going to jail was worse than not helping someone.

This article has a pretty good summary, which I'll quote here:

This curious but important tale begins on the morning of Nov. 20, 2006, when Xu Shuolan, a 65-year-old grandmother stepped off a bus in Nanjing, and fell to the ground. Just behind her was Peng Yu, a 26-year-old student. While others passed her by, Peng –- a self-described Good Samaritan -- rushed to her aid, accompanied her to the hospital and even paid her modest bill.

In thanks, Xu Shuolin -– a woman of modest means –- sued Peng for roughly $7,000 in medical expenses she claimed were due to the fall, including broken bones. The judge, in turn, invented a new “everyday experience” standard in the law, suggesting that nobody pays a stranger’s medical expenses without a guilty conscience. And on that basis, he ruled against Peng Yu, turning the case into shorthand for the decline of Chinese morality.

The situation gets weirder if you read on, but most people missed that part and only remember the original case.

There are many such cases in the news, including one where a man fell off the bus but in the doorway, and had to basically say "It's my own fault. No one else is to blame. If you help me I promise not to sue" and only then was he helped.

So it's a major issue. Not not one that goes too far back into the past. I was in Nanjing when this was going on and it really spooked people.

But, if you want to re-ask the same question specifically in terms of the past, that'd be totally cool. You can even just edit this one to remove the recent stuff and I'll re-approve it.