I've met a few people in the US who will nod and make some sort of acknowledging sound after every sentence (or more often) you say, so while rare, it's not exactly something I've never come across.

A lot of hai’s is what one end of a polite Japanese conversations sounds like. In my experience Japanese friends speaking casually say it much less, unless one of them happens to be on some extended monologue. From this perspective one reason English speakers use acknowledgement much less is that conversations coded as formal or polite are much rarer.(think how you respond to a desired job offer, chances are you would be very active in frequently expressing positive assent).