There’s another issue that follows from the OP; the relation between where the lines are for oneself and for someone else. Some people are much more machmir on others than themselves, others do the opposite and often the same person does both depending on the situation.
For example, how many men reading this have “shushed” someone during davening in the past year? I’d say most, including me. How many people have talked during davening (including the technically permitted-by-loophole parts) in the same period? Same answer.
I’m guessing that the equivalent for women would be seeing someone’s makeup and thinking that it really isn’t tznius.