That formal etiquette being replaced by common-sense etiquette can be shown by this accepted rule:
A.
Men should always open doors for women.
B.
A man should assist a woman into a car any time they travel together.
C.
You should give up your train seat to a pregnant or handicapped rider.
D.
Men should always open doors for women. A man should assist a woman into a car any time they travel together. You should give up your train seat to a pregnant or handicapped rider.