I think all the sex-based US military laws have been reversed.

Girls still do not have to register for the US draft. Boys, however, do.

Sorry, I just used examples that first came to my head, but I'm not from the US. I assumed you would have some as well.

And yes, a lot of them should be looked at and changed.

In an ideal world people would be disqualified from these positions if they were bigots. But good luck getting any trans friendly protections on the books. People over the past decade have become way more comfortable in harassing trans people in public in a general sense. Enforcement is also spotty. Airline security particularly is given a lot of benefit of the doubt and not an amazing amount of oversight. Systemic persecution of Muslims has been an issue for decades and surprise - people still get hassled. Police, police unions and the courts of law they serve are also often very good at covering for each other.

In reality these issues apply on a worldwide scale. If you are traveling by air and have even a layover in a country where it is not safe to be openly trans you are in danger every time someone asks to see your documents.

Also every border guard or police officer in every country is a patchwork. All it takes is one particularly bad one and you could end up with PTSD, injured or dead. There is good reason why police officers in uniform are generally not welcome at Prides. It is a known trigger that causes folk who have experienced this kind of violence to have involuntary flashbacks or panic attacks.

It is ultimately safer to give someone the tools to be safer than to trust every official in every country you might ever want to risk visiting to be a good official. Even if you are going to one that is supposed to be safe.

Depends on the country how often those documents are actually used. In some places (like Canada or the UK for instance) your birth certificate needs to match those other documents or else you are SOL getting your passport and driver's license updated. Otherwise as a document it can also play a role in applying for government services or schooling in a lot of places which means you can get misgendered during times where you are already under duress or opens you up to being forcefully outed to post secondary administrators and teachers.

Medical records are usually better served with more accurate information because if you've transitioned your reactions to medication are more closely linked to your horomones meaning the dosages you receive by any trans health untrained doctor may be off and it is actually safer in most emergencies to have their first instinct be to treat someone as their listed gender and not their birth sex.

From a beaurcratic standpoint listing the sex of someone on their birth certificate isn't exactly useful past a point either. The main purpose of the things is to establish a time or location of the person's birth for determining nationality. That's why you can change your name regardless of what you were called at birth, so it remains a reflection of your current state... Also census data logs everything at your registration so later changes don't impact anything significant. The other reason birth certificates exist is for enthusiasts to track genealogy.

There isn't exactly a compelling reason to disallow people some autonomy over how they are recorded for posterity sake... aside from a lack of empathy.