Some schools only require English proficiency test if HS language of instruction is not in English.
For example, UCSC:
http://admissions.ucsc.edu/apply/international-students/english-proficiency.html
Some schools require English proficiency test if English is not native language.
For example, USC:
https://dornsife.usc.edu/international-application-process/
UCB recommends English proficiency test for all international students:
http://admissions.berkeley.edu/internationalrequirements