It's not appropriate to divulge many of the numerous tactical situations where an 'inadvertent' RA could occur
Tickets...
Lots of aeroplanes all quite close to each other flying through the middle of the London TMA. Now tell me how that would work if all the heavies fitted with TCAS flew in TA/RA?
Yep, TA it should be. "Traffic Traffic Traffic Traffic Traffic" "Derek, tell that thing to shut up!" "I can't Nigel, as you told me to put it in TA!" "Orright Nigel, tell the king to move away from us a bit!"