When you apply ED you are signing a contract. (usually the student, parent and school counselor) There are steps involved so one cannot say the ‘accidently’ did it 
Though it is not legally binding- breaking contract can have many negative outcomes. (mentioned up thread already)
Paying the deposit on an EA acceptance and then backing out because you got off of a waitlist is allowed. When applying for schools on the common app- this is one of the things you agree to
