The law doesn't group people because they are identical, it groups them because they face the same specific type of discrimination.
I have already explained in several posts that, as far as the PC of GR is concerned, that I do not believe this to be the case, ie. they do not "face the same specific type of discrimination".
Removing the category doesn't help your hypothetical pregnant lesbian
I did not suggest that it would. What I said was that the current system is unfair by including a redundant PC of GR that creates unnecessarily privilege.
it just ensures that when a trans person is targeted for being trans, the law is forced to pretend it didn't happen.
"Trans" is a culturally bound, unstable social construct, unlike Age, Sex, Pregnancy, Sexuality, etc. It is therefore debatable whether "transness" should be legally recognised in the same way as other characteristics that attract protection from discrimination. That does not mean that people who claim a trans identity should not be protected from discrimination.
Hypothetically, if the PC of GR did not exist then a person claiming a trans identity and alleging unfair discrimination would know, depending on the nature of the discrimination, which of the remaining PCs applied.
The law would not be "forced to pretend it didn't happen".
Application of the law would instead clarify the basis for discrimination in terms of characteristics shared with others and this could be reflected in statistical analysis.
For example, annual statistics for successful discrimination cases could state the number and percentage of males claiming a trans identity vs females claiming a trans identity who were unfairly discriminated against on the basis of:
- Sex Discrimination by Perception
- Sexual Orientation
- Disability Discrimination
- Belief Discrimination
The first of those is already much more likely to be alleged by someone who claims a trans identity and very unlikely to be claimed by anyone else.