It was fine to say a woman is someone with a vagina and a man is someone with a penis in the past and now you consider this hate speech.

Still is fine, you wont go to jail for accidently misgendering someone. At worst you may illicit an awkward cough in the room and maybe someone will take you aside later and be like "bruh they are (other gender) haha" and you would be like "Oh shit! My bad!" and that should typically be the end of it.

I'm a dude with just very long hair, cuz I like its style. I get misgendered all the time from the back, people call me a lady or ma'am all the time.

When they see me up close they often go "Oh geez Im sorry!" and I just laugh and tell them not to worry about it, it happens all the time. Thats about it. Thats the whole interaction.

Thats right, misgendering happens to cis people all the time too, and this type of social interaction is an ancient one that has been around for a millenia.

No one actually gives a shit.

Now if you PURPOSEFULLY misgender someone to try and hurt them...

That is actually a fucking problem and now you are being an asshole. But thats not just for trans folks! That applies to cis people just as much.

Let me ask you this: You walk into a bar with a biker gang, and a big burly dude is in there and you call him a woman, and he informs you sternly (cough) that he is a man, and you keep calling him a lady and are clearly trying to piss him off, you tell me how well that will probably turn out for you.