Channels editing tv shows

CastorTroy

Was wondering why some channels edit shows that other channels wouldn't? 2 channels I can name are Universal and Watch.
Was watching last week's Royal Pains that I recorded off Universal and there's a scene where Hank sticks a needle in someone's arm but it didn't show the needle going in.
A couple weeks ago, I watched an episode of Grimm and they edited out a couple parts which contained violence. Understandable if on during the daytime, but was after the watershed.
And another time was watching The Mentalist and they edited a fight scene.

I know these from double checking with the original cuts.

But what stands out with these shows, well maybe not Grimm, is that they're not exactly The Sopranos and air in what I would think is the stricter USA without being cut.

I mean why cut them at all? Especially when terrestial stations like UTV and BBC are airing more violent/controversial material in their soaps.

Comedy Central are getting on my tits for this, getting rid of "bitch" and in an episode of Scrubs the other day I noticed they went from silencing just the "ass" part of "jackass" to all of "jackass". Ridiculous.