Oh, that's sort of what I was expecting. And your last point makes sense, too ^^
Most of my family is from the south, and I know some are lactose intolerant whilst others are not. Unfortunately, that's all I can really say. I looked up just now if cooking milk reduces lactose, and it seems like the answer is yes. I didn't find anything about frying specifically, but
Healthline says, 'Because of the changes in protein and lactose that occur when you boil milk, people who have milk protein allergies or lactose intolerance might find it easier to digest.' Basically, it changes *some* of the lactose to lactulose, it doesn't just strip out the lactose.
Also, I like that it comes up as a Cantonese dish because it is eaten more in the Cantonese-speaking parts of the south, not just the south in general. I should have been more specific about that ><