Because hr doesn't care too much about whether you change your major, what you care about is what major you graduated from and whether it meets their application conditions.

The reason is simple: hr is also a human being, a migrant worker and not a spy, and will not care too much about all your school experiences. Moreover, hr also has a lot of work to do every day and a lot of resumes to read. If you add another sentence, it doesn't mean much, and it is likely to be passed.