A few thoughts on it:
a) many coffee shops, including well-known chains in the UK have only the one toilet which is used by customers, some have two, one for men one for women, usually if they are larger; aeroplanes and trains just have the one toilet used by all.
b) airports and also some (large) railway stations have toilet facilities for men, women and a third which has a small table to make it easy to change a baby's nappy- a transexual I was travelling instantly chose the baby-changer unit when she needed the loo -and many/most in large facilities also have large stalls for the disabled, so in a sense we already have a 'toilet culture' that can adapt to diverse users.
c) While I can understand why some women would object to a male-to-female transexual using their facilities, assuming they took any notice of it, I am more concerned by those men who seem to think a public toilet is an all-hours sex club where they can jerk off in public and invite another man to share a cubicle.
d) a solution would be for there to be public toilets which are large enough to accommodate diverse users with the essential part being staff who not only keep the place clean but also monitor users, and may also be trained if the user is disabled, an elderly person with dementia or some other manageable issue. The problem is one of the law -should it be a legal requirement on local councils to provide public toilet facilities?- and financial -the UK has lost something like 40% of its public toilets in recent years.
This is an interesting article on it, with additional references to the US situation -
http://www.newstatesman.com/politics...public-toilets