There's a lot of nonsense spouted about this. We are genetically programmed- our chromosomes (XXY and that stuff) tell us whether we are male of female, despite what we may 'feel' we should really be. If someone has male chromosomes and feels they should be a girly and wear bikinis and make-up and frocks, that's their business. If they cannot conform to society and present themselves as what they really are, then they will be regarded very much as 'odd' and treated like a pantomime dame. That is how it is. If they are biologically a 'he' and want to be called a 'she' and dress up as one, then that is not really enough to be called 'female' in official documentation, and this is reflected in the official UK system.
Whilst we may try and convince ourselves everyone accepts this, I can confirm it is not so. I have flown as passenger with one such person mentioned above. My opinion is that most people around me were uncomfortable with it and reacted with derision. I think there is little biological basis for it- it's more a psycological need to dress up. Nature has decided which you will be- you cannot just override that.
There is a similar girl in BA. BA dont have any problem and I think colleagues are sympathetic.
I think it is more afraid to say what they really think.