Can people cheat on the ACT/SAT? Yes. Do they? Yes. Does that mean that standardized test scores should be discounted? No.
The essays aren’t about grammar and spelling. They’re about stories, perspective, and experiences. BYU outlines that these essays should be written by the students themselves. They expect honor and integrity out of applicants, which makes sense considering the standards of the school.
Another great thing BYU does to sift out students is require five essays. This is a deterrent to many students. If you’re not willing to put in the time to write five essays, then maybe you really don’t want to be at BYU. And that’s okay. This is a part of the reason why the acceptance rate at BYU is so high in spite of the high average test scores and GPAs. Lots of self-selection that happens.