Another problem is the increasing complexity of airspace and 'local' procedures.
Invariably these things have a negative impact on safety since people become more concerned with watching out for airspace boundaries (which contrary to opinion don't hurt if you bump into them compared to looking for other a/c which hurt a lot if you happen to end up sharing the same piece of sky.)
This leads to more and more people becoming reliant on technology such as GPS rather than looking where they are going.
Add all this complexity to the fact that people are flying less and less often because of the cost and you'll find a pretty nasty trend emerging.
I personally don't know many PPL's who "rely on TCAS" simply as it isn't fitted to the vast majority of light aircraft. Personally, when flying a machine equipped with TCAS, if it goes off and tells me to do something, then I'm going to do it. All commercial aircraft have it fitted and in certain circumstances we are 'reliant' on it. I certainly wouldn't want to trust the safety of my passengers purely to the MK1 eyeball.