Why does satellite radio(Sirius) have so many commercials?

I borrowed my brother-in-laws because he's out of town for awhile and I thought satelite radio was all about being commercial free, why exactly does someone have to pay to hear commercials. I know there are maybe a tad bit less, but come on. I do like that it's not censored and you can hear the artists real songs though. I don't think I would pay for it though.