Again, this is what the school wants to know
How much cash do your parents have? it does not matter if it is in the bank, in a can buried in your yard or stuffed in the mattress. Bank statement are a source of proof from a neutral third party.
Again, schools are looking for confirmation and documentation of assets. If your parents aren’t able to confirm this money, then as I stated previously, you are going to have problems with admissions (at schools that are not need blind to international students) and financial aid