but it's not like a quality comedy script is a whole lot more work or money.

Ummm... wow. It might not necessarily be a whole lot more money, but despite what your friends/family might tell you, writing is hard and you probably suck at it. Comedy writing is harder and you almost definitely suck at it. Most people do. It's not like a guy, even a rich guy, can just wave a stack of bills at an agent and make a script not suck.

And once you have a script, it's even harder to find a director who doesn't suck at realizing the script in a funny way. Do you know why sites like college humor and funny or die exist, and have mostly short videos? Take Funny or Die specifically. There are many famous and talented contributors on that site. There are many reasons why they contribute there, and one of them is because it's a lot easier to start off with short productions, and it's not just because of the budget or work. It's because things that are funny by themselves don't always work in a movie. You can make a movie that's a string of really funny scenes and moments, but still have a shitty movie. And that's if you're even good enough to write the funny moments in the first place.

I don't think I have to go through every single aspect of producing a movie and how each one can kill the humor, but let's say you get a good script, a good re-writing team, good sets and camera work, good directors, good actors, good crew in general, and you set out to make a good movie. The movie can still bomb, audiences can still reject it, even when you've done things right.

The fact is, comedy writing is hard. It's hard enough to tell what a group of people you're standing in front of is going to find funny for 2 hours. Thousands of people in movie theaters? Forget about it. You say it's not much more work to have a good script. I say most of the time, no one's really sure which script is going to be good.