Lying on the common app about your parents’ education or anything else may be tempting for various reasons but doing so can have very serious consequences, up to expulsion, rescinding of your degree, etc. I doubt people lie about that anymore than they lie about their race or ECs or anything else, and any lie is, IMO, not worth the risk of getting caught.
FWIW our GC in a large public school DID ask, via the form families filled out before she wrote her recs.