She can do the same things in the toilet too, can't she?

Yes, but that image isn't as directly conjured up by the word toilet.

I'm also not saying that the term ladies room will never conjure up the same image just that it is less likely to do so.

Furthermore, if you are in a culture where some people use euphemisms while others do not, you signal something by your choice to either use or not use the euphemisms.

Of course what you signal is different when you are conscious that the other person consciously notices that you make that choice than when it happens on a more unconscious level.

(Why are specifying Great Britain, anyway? How different are things in NI than in the rest of the UK? I only spent a few days there, hardly any of which watching TV.)

I didn't intent any special meaning there.