Why are transgender people treated differently than those who claim they are "transracial" or "transage"?

Race is a myth, you can identify as any age.

In a sense, all of us are small children inside, so that's something which is not so much a medical condition as universal. We all have issues as adults of having difficulty coping with taking adult responsibilities for things and it's tempting and even therapeutic to do that from time to time, something we should make our peace with and not beat ourselves up about. The transracial thing only happens when someone is brought up in an environment unusual for their ethnicity, and is entirely culturally determined.

Regarding trans gender people, it amounts to one of two things. In one set of people it's merely about not wishing to be boxed in to a particular gender expression by pointless societal pressures. In the other set, it's to do with not being able to be mentally healthy with the endogenous balance of sex hormones, so it's more like hyperthyroidism causing anxiety or diabetes causing depression. It amounts to being a neurological condition.

Translating that into the trans age and trans racial thing, there is no innate difference between brains of people with different ethnicities and nothing about their internal environment which makes them different from each other, and with age, there are developmental delays, so an example of someone who is a child in an adult's body would be a person who is learning disabled. But such a person probably wouldn't express it in that way due to lacking the mental capacity to be aware of the issue.

On the trans-age thing, there are adults who are actually mentally a child. Its called an intellectual disability. My aunt is 35 but is mentally about 4. She is literally like a 4 year old and needs the same care as a 4 year old. To see these normal adults pretend to be a child is ridiculous. You cant just decide one day to be a child. If someones brain is mentally adult, they are an adult.

Gender is sort of the same in that sense. You are whatever gender your brain is. Gender has nothing to do with a persons body (their sex).

"if someone wants to dress as, act like, and even transition to the opposite gender, in this day and age not many people are going to stop them"

People can dress however they want and it actually doesn't even have much to do with gender. It shouldn't have anything to do with gender.

How do you even act like a man or act like a woman?

Nobody changes gender. They just change their bodies. Honestly its no different than fixing a cleft palate. Just something people are born with that isn't right and needs to be fixed.

You're laboring a point under the false assumption that transgender identity is a mental illness. Gender dysphoria is not classed as a mental illness because it is simply the stress that a person experiences due to the underlying condition. That underlying condition can often be seen as more of a kind of intersex. Believe it or not the human brain biologically develops instinctive traits that are factors of a person's gender, it's not just psychosocial factors. When fetal development goes wrong such as the case of hormonal imbalance in the womb, this can alter the way the brain develops. There is even strong evidence that hormonal treatment doctors give to prevent miscarriages can increase the risk of the child being born transgender. Granted there could be the case of an identity crisis that stems just from psychological issues which would be approaching the same sort of bracket as those other disorders you mentioned but therapy can determine the appropriate diagnosis.

trans age, trans racial and trans species people ONLY exist to make actual transgender and nonbinary people look bad. There's NO history behind them and NO validity to anything they claim. Every single example i've ever seen the individual has turned around sometimes minutes later and said derogatory things about transgender and nonbinary people.

Because someone wanting to be another race has racist implications and shows a mind controlled by racism.

EDIT: I get what you are saying but when something has racist implications it is taken differently then what may have sexist implications and someone wanting to be the opposite sex doesn't say sexist in most people's mind even if they do not particularly agree with transgenders.