Why's it so hard to butter toast with a steak knife?

Every time I try to spread butter or jam over a slice of toasted bread using a steak knife instead of a butter knife, I never seem to be able to spread the topping that evenly.

I know I could figure this out if I just used my brain or paid slightly more attention while buttering the toast. But if I went to that effort, I could have just as easily gotten out a proper butter knife and made the whole issue moot, and I'm definitely too lazy to do that, so here we are.

Slight caveat: the steak knife in question is non-serrated, if that makes any difference.