In America, for many high school graduates, undergraduate applications are not the "final decision."
Transferring schools is a common phenomenon; reasons such as dissatisfaction, poor fit, remote location, or limited school resources, among others, can all be motivators for students to transfer.
Although the acceptance rate for transfer students might be lower than the freshman admission rate, a large number of students still manage to transfer into their dream schools in America every year.
As for the transfer system, every university in America has an open attitude towards it. As long as you meet the criteria, you will be considered for admission.
And when you complete your four-year course or receive your degree through transfer credits, there will be no difference on your diploma from those admitted through entrance exams.