why-

what exactly is your problem here? because as far as I can see a trans person deciding to change something about their body has literally nothing to do with you.

'I don't want to call them by a new name/pronouns'
And yet when Sean Combs changed his name to Puff Daddy/P Diddy/Diddy and back again to Puff Daddy everyone was ok with it. Get over yourself

'They make me uncomfortable'
You make them uncomfortable. People make people uncomfortable. Get over yourself

'I don't want to share a bathroom with them'
Either way a trans person who has transitioned is going to be using a stall. No one's going into bathrooms and whipping out their junk. Trans people have the right to take a damn piss. You run into a lot weirder people in the toilets than a 'guy' in a dress

'It goes against my moral beliefs'
Now look, there are some morals that are generally accepted by society to be objective truth, like 'murder is bad'. Things like that are upheld because they're made into laws. People changing things about their body is not one of them. Otherwise people wouldn't be allowed to go on diets or get tattoos or piercings. Your views don't run other peoples' lives

'People should just stick to what they're born with'
By that logic I should weigh 4.25 kg and have no hair. People change. Get over it.

'Being transgender causes people to commit suicide'
No it doesn't. Abusively forcing trans people to behave and dress and look a certain way that goes against how they feel is what causes such a high rate of mental illness in trans people. Let your kids develop on their own and they'll turn out fine.

It's none of your business what's between someone's legs. Just leave them alone