Why don't many cameras come with self-timers?

I've looked at the different brands and styles, from film to digital and disposable, but it seems like only the expensive ones come with self timers, and not the cheaper ones, but every camera has a basic flash on it. Why is this?

NOT SO FAST!!!

Most digital cameras I've seen DO have self timers (I teach digital photography classes).

You might have to get into the menus to activate it, but the vast majority of digital cameras, I've seen have self timers. And they aren't all expensive cameras.

Even my 1st digital (Fuji 2MP) had a self timer.

READ YOUR MANUAL

I have a really, really cheap digital camera and it has a timer. They're often there, but hard to find--you need to read the manuals, which is dreadfully dull.

I'm not sure what you consider expensive, but the Kodak EasyShare C643 does come with a 10 second timer on it. I think it was only $250.00 dollars at Wal-Mart. It's a 6.1 maga-pixel, and it takes excelent pictures. It also take movies with sound. I'm very happy with mine.
I hope this works for you

High end cameras are more apt to be used by a serious photographer than cheaper entry level cameras.