Why cartoon characters always wear the same outfit?

Because if they didn't, the artist would keep having to come up with new outfit ideas and keep having to draw new things when they don't really have time for that

I guess so they can have that original outfit that everyone can see it somewhere and be like: "oh yeah, that's ____________ outfit!!"

But Mabel Pines from Gravity Falls is the only cartoon character I know that changes clothes. Watch a few episodes if you don't believe me.

definitely the comic strip series 'completely Spies' ; the characters have diverse clothing each and every episode, the only clothing that stay an identical are their secret agent uniforms. yet each and every episode, counting movies, they positioned on some thing diverse. all of them do.

So people can recognize them!