system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Why doesn't Tony Stark build Iron Man suits for Hawkeye, Black Widow, or even Captain America?

Edit: Awesome answers, folks. I'm still not convinced about Hawkeye, but I'm willing to concede that it's probably not a great idea for Cap and Black Widow.

Also, I did tag this as Marvel Cinematic Universe (that's what MCU stands for, right?), but I'd love to hear if/how this question may have been addressed in the comics as well.
gpt
They all kinda have their own thing and really its also just Tony's narcissism, he is the only one good enough, and capable, to operate an iron man suit effectively.  He didn't even wanna give his best friend Rhodey one.  Rhodes took a suit against Tony's will and ended up proving he was proficient in its use so Tony thought alright thats cool.