Why are porno flicks called adult movies?

i don't get this one at all. alright there are hundreds of movie channels devoted to porn. why can't they just call them what they are? imagine your child is watching tv,at around 10pm on "cartoon network";and inadvertently watches one of those advertisements endorsing "adam & eve",or "spice tv",and these are called adult entertainment channels. this could be quite confusing for a 10 year old. the kid might think that this is all adults do. it's really sending the wrong message. the word adult is actually quite broad and expansive encompassing all forms of entertainment. for instance; drinking,rated r films,voting,joining the military,working at home depot,to name a few. in other words,these activities require adults to do them. just call it what it is. it's a PORNOGRAPHIC movie. and last time i checked,pornography wasn't a bad word,nor was it a derogatory word. i mean seriously,who are they trying to kid?