They can't imagine talking to a trans person.

This seems like a jab but I'm just not getting it.

It's not a jab. I am directly alluding to the fact that you are clueless about the actual dangers being discussed here, because you are so insulated and removed from them that they seem like vague abstractions.

Trans person: "These people are passing laws to strip me of human rights. Some call for my death, while others actively try to kill me and others like me."

You: "Have you tried harder at being friends with them? Sounds like you just have a bad attitude."

Why can’t a trans person “make friends with someone who hold beliefs different than their own”?

Nobody is saying “make friends with someone who hates you”. That’s true of anyone.

But can a trans person make friends with someone who disagrees on that minors should be able to start transition therapy without informing their parents?

Sure, why not?

If you can’t be friends with people who don’t hold 100% of the same political views you do, you’re going to have a very lonely life.

Note the word “maybe” and it might be easier to read charitably.