I think it is a "tradition" of certain British family, perhaps not all of them though. I was quietly horrified when my ex kindly offered to wash the dishes, then he simply dipped the dishes in soapy water, a little scrubbing or swishing about and took them out of the soapy water to dry. He suffered ME (or CFS) so I supposed that was the best he could do, so I didn't say anything and rewashed everything later. However I was doubly flabbergasted (in silence though), when I saw his mother washed the dishes exactly the same way.
Elsewhere, the dishes and pots and utensils and everything that have been washed with soap is thoroughly rinsed with warm-hot water all the time.