aluminium shuffler - As for the notion that US controllers expect a pilot to listen and know what all the other aircraft are doing, that is entirely the controller's job - they are the ones with surveillance radar and ground movement radar, and a seat and set of windows that aren't attached to a platform they're also controlling moving in three dimensions at a couple of hundred miles per hour... Good pilots will try to build an air picture of the traffic around them in easy conditions, but when the weather is bad or bits are falling off, or they're visiting a field with unduly complex procedures (ie most of the US) for the first time, their focus is going to be somewhat narrower.
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Expect is the wrong word. Maybe saying "it benefits the pilot to listen to a/c ahead of their aircraft" would be better. It provides basic situational awareness benefits. TCAS has been a wonderful addition to a pilot's SA ability.