Avoidance of scenarios like this one is why I love TCAS so much.
Yes I know that some aircraft are not transponder equiped, and also that there are still people out there who neglect to switch their transponder on, or activate mode C but most traffic (talking on LARS frequencies in the Southwest) appears as a little blip on my MFD.
I can think of at least 3 occasions in the past year when I have been thankful for it and it has definitely saved me from airproxes if not worse.
And yes I still look out the window...
Now all I need is XM:WX weather radio or onboard weather radar...
SB