I think the whole idea that you would feel better if there were an equal number of Muhammad jokes is sortof a red herring. Would you really feel better if it's only someone else that's being laughed at?
OK - I guess you probably would. But here's the point. American comedy of this kind is usually about "us". Most comedians laugh at themselves, or the culture they grew up in. Jokes only work when the subject is familiar. I don't think most of us know enough about Islam to come up with a decent punchline, beyond that which is satired about Muslim countries now.... The parts that touch us.
What you don't realize is that if you are the subject of comedy, you really are the mainstream. We joke mostly about ourselves. Jews tell jew jokes. Blacks tell black jokes. Hispanics tell Hispanic jokes. Catholics tell Catholic jokes. My hunch is unless and until there is some Arab comic who tries it, Islam jokes mostly will fall flat because few would be able to identify with it.
Tell that to the Austrian jews...
Among the most eye-catching displays is a fairground shooting stand depicting a Jew and a ferocious dog. By hitting the target, shooters set off a mechanism that sets the dog on the Jew, who uses an umbrella in an attempt to fend off the attack.
There is a word for it Schadenfreude: "Pleasure derived from the misfortunes of others."