I live in Australia now, and we have 2 sinks, but I've never used the second for rinsing. The few times I've tried it elsewhere, (A) it seemed like a waste of water, and (B) after the first few dishes, the second sink was full of suds, which rather negated the rinsing anyway.
That would to me be an indication that they do need rinsing.
I rinse under running water, but when we are camping, I can rinse the dishes for a dinner for four in less than a quart of hot water. (We have to carry the water in and boil it ourselves - believer me, we don't waste it!)
There is also a difference between dish soap and dish detergent. In the US, most of us use detergent, which can be toxic if not rinsed off. I think too much soap simply causes a little gastric distress, but if you guys use soap and are used to it, I guess not.
I am not trying to be critical, just explain how we think.