There could be a few reasons why Brazilians may not voice out their frustration in English:
1-Language barrier: Many Brazilians may not be fluent in English, or may not feel comfortable expressing their emotions in a second language. It can be difficult to express complex emotions and feelings in a language that you are not fully comfortable with.
2-Cultural differences: Brazilian culture and communication styles may differ from those in English-speaking countries. For example, in Brazil, people may be more indirect in their communication and avoid confrontation, whereas in some English-speaking countries, direct communication is more common. This can make it more difficult for Brazilians to express their frustrations in English.
3-Context: The situation and context in which the frustration is occurring may also play a role. If the frustration is related to a specific issue or problem within Brazil, it may make more sense for Brazilians to express their frustration in Portuguese, their native language, rather than in English.
Overall, it's important to remember that language and culture are complex and there may be a variety of reasons why Brazilians may choose not to express their frustrations in English.