I can't find any evidence to support that.

High-Temperature, Short-Time (HSTS) Pasteurization appears to be the standard in both Ireland [1] and the US [2] -- 71.7°C / 161°F for 15 seconds.

And I can tell you from personal experience that US milk goes bad in days as well, and has for decades. I don't know where you're getting the idea that it lasts a month in the fridge.

There are real differences in some foods between the US and Europe, e.g. American eggs are washed while European ones aren't. But fresh milk from the supermarket appears to be very much identical.

[1] https://ndc.ie/accordion/what-is-pasteurisation/

[2] https://www.usdairy.com/news-articles/why-is-milk-pasteurize...