As Zooey correctly points out, appearance ('presentation') for both cis and trans people will get you questioned if you don't match up with someone else's stereotyped view of how a particular gender is 'supposed' to look. If you want to avoid issues, you either have to go with gender-neutral facilities (no questions) or with potty police (based on ID). The latter option, of course, puts pressure on trans people who haven't or can't obtained revised ID and on gender-nonconforming people (non-binary, gender-fluid, agender, intersex, etc.). The objections to the former are 'morality' (primarily religious beliefs &/or prohibitions) and fear-mongering. Whichever you choose, somebody will be discriminated against.