Hibler, your hypothetical is a little weird given that my wife wouldn't know what "equipment" another user of the bathroom would have unless she opened the stall and inspected that individual's genitalia. Do members of your family do that? Mine don't either. 

What is a common practice is for dads to take their young daughters into the men's room, moms to take their young sons into the ladies room, caretakers taking disabled individuals of the opposite sex into the 'wrong' restroom, etc. And I have been to plenty of events where the lines for the ladies room were long and the guys were totally fine with women using the empty stalls in the men's room. 

Is that going to be illegal now, too?