Sometimes you catch typos while writing; sometimes you don't. It happens all the time when people write essays, and that's why you have other students and the teacher proofread them. I know it happened to me a lot during my high school years in my Freshman English, Sophomore English, Junior English, and Senior English classes.
Typing on a phone can be very aggravating. Most of the time I type from a phone the post is littered with typos, but I just leave them because I don't have the patience to go all the way back and change them and deal with the frustration. of course I wouldn't leave a title misspelled.