Things are not so cut and dry. For instance, did you know that a diet which includes fermented dairy populates the gut biome with bacteria that will break it down for you[1][2]? And that the placebo effect plays a role in symptoms of lactose intolerance[3]? The idea that milk wasn't drunk in East Asia in antiquity is a misconception as well. It was artificially dropped in Ancient China while assimilating pastoral societies as part of a larger scale dietary reform[4].
Additionally, cow milk represents a single dairy product amongst a plethora of ones. Everything from Horse milk to Goat's milk is consumed globally, and much dairy is consumed as further processed food like fermented milk, yogurt, cheeses, etc. which generally aren't considered by Americans when talking about dairy, for whatever reason, even when supposedly attempting to "unplug" from the dairy industry's propaganda.
Moderate lactose intolerance might also be a symptom of Western diets rich in processed food. I also had it for most part of 15 years. Then I discovered that I could drink whole milk in small quantities if combined with cereal or cacao. During this time I continued to consume yoghurts and other dairy products. For a time I even made my own yoghurt or kefir because I could not consume whole milk so it was only logical to ferment it.
It's more prevalent in South Eastern Europe, where people have traditionally fermented the milk into yoghurt for centuries. The US is actually on par with France, they might make it more of an issue than it is.
Additionally, cow milk represents a single dairy product amongst a plethora of ones. Everything from Horse milk to Goat's milk is consumed globally, and much dairy is consumed as further processed food like fermented milk, yogurt, cheeses, etc. which generally aren't considered by Americans when talking about dairy, for whatever reason, even when supposedly attempting to "unplug" from the dairy industry's propaganda.
[1] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4066025/
[2] - https://pubmed.ncbi.nlm.nih.gov/15277142/
[3] - https://gut.bmj.com/content/41/5/632
[4] - https://www.asianstudies.org/publications/eaa/archives/china...