Who the heck told you that? Yes they are supposed to be reported! Well, depends on how you won them... its called a W2-G form. Found that one out the hard way! lol.
in large casinos, most dont W2-g unless you have 5k in ONE cashout..
now some small cainos have a $1k W2-G trigger
some vegas ones dont W2-G until you cash out 10k or more..
it differs everywhere
i learned the hardway too.
i did a damn 11k cashout, with a 9k buyin, them bastards was trying to tax the entire 11k, instead of the 2k profit/winnings