I think in Thailand there is a certain mentality of just standing toe to toe and blasting each other, its like a machismo thing or something, it sometimes give the appearance of being "untechnical". In Muay Thai aggression is favored in scoring, so I'm sure that plays into it as well.
The subtly of movement in muay thai is an element as well, its not like boxing because there are so many more angles of attack, you can't go too far in either direction, or lean over too much. Its more about head movement, and yes angles especially.
If you don't realize thai boxers are using switch kicking evasively and to adjust angles, its because you are used to watching boxing it doesn't make sense because you don't know what to look for.