Vietnam very much has overtime issues. Americans work more hours than Japanese. Many Viets work 6 days a week at typical office jobs which is more than both countries. Vietnam is currently rapidly trending to under replacement-level births.

I chose those examples because I’ve worked in each, but hours worked and birth rates really aren’t too relevant here. Vietnam was a nice country, but be honest: you wouldn’t want to live there making an average wage if you had a choice of living in a typical US or Japanese town with decent infrastructure and average wages.