Times are changing. At one point braces were very uncommon with children and almost never seen with adults, than braces got more common with children and some adults started getting braces. Now in some countries it seems to be that most children get braces at some point and even in adults it is not very uncommon. People get embarrassed if they stand out from the group, so since more adults are getting them and in some countries most people will know at least one adult who wears braces. People tend to respect adults wearing braces and envy them for having the courage to fix their crooked teeth.