Your example of head movement in Muay Thai is a link to a BOXING match? :icon_neut
Vera's statement needn't be taken so literally. Of course MT has head movement and footwork, but in general, compared to a more evasive boxing style, obviously, much less.
Watch your average Muay Thai bout. There's a lot more plodding forward and standing around, as well as blocking and absorbing blows than your average boxing bout, which has a lot of "boxing" and dancing. Does that mean there aren't evasive nakmuays, or brawling boxers? Of course not. But in general, it's just the nature of the sports.