I lived the first 25 years of my life in the UK and drank pasteurised milk almost exclusively and found the taste of UHT to be lesser.
I then lived in Poland for two years and drank UHT only.
At first I disliked the taste of UHT but over time I grew accustomed to it.
I am still able to tell the difference between pasteurised and UHT, I just no longer mind.
I find that for many things in life where there are similar but not exact variants, one tends to prefer the variant one first tried despite both variants being potentially equivalent.
Pasteurised milk vs UHT is one example. Margerine vs butter is another (I was raised on margerine and disliked butter for years). Windows vs Linux desktops (again, I was raised on the former and initially disliked the latter despite both being generally logically equivalent).
I have since learned to be more accepting of the differences in variants of food and tech. This seems to make life easier for me.