Another possibility is that people do remember that evenness has to do with divisibility, but they have too many concerns about divisions involving zero. Perhap

Another possibility is that people do remember that evenness has to do with divisibility, but they have too many concerns about divisions involving zero. Perhaps they inadvertently exchange the divisor and the dividend and end up thinking that the parity calculation involves division by zero. Or maybe they remember the rule against division by zero too broadly and think it applies to zero as a dividend as well.