'sleeping with' vs 'having sex with'

[ensho]

sex is out there in the media plain as day.

so why is the act of sex referred to as 'sleeping with' instead of 'having sex with'?

on the talk shows, celebrity gossip, etc. they say 'sleeping with'. so and so has slept with x number of partners and so on.

you can see porn, talk about porn.

but when talking about a person or couple it stays to 'sleeping with' and not 'having sex with'.

I find myself yelling at the TV 'they are having sex, they are not sleeping'.

am I the only one annoyed by this?