A half descent lookout from both might have resolved a few issues...
Radio's are only a backstop for 3 reasons:
1- Ive flown enough piece of sh1t aeroplanes to know the radio is a good chance to be the first thing not to work correctly.
2 - I cant tell you how often Ive seen/heard student pilots chatting away and not listening on centre freq blissfully unaware they cant hear or be heard by the people who need to hear them in the CTAF.
3 - forgotten calls.
Not hearing anything is an excuse to look harder.