I think the reason they fall under the scam is because the sites are not analyzed well. It is normal to use ToS but the gamblers have to check properly they fall into the trap of cheating with various information.
Not always mate, their are times where one will follow up all the do(s) and don't of a Casino and still fall into the trap of the Casino freezing the gamblers funds, most times this is all depends on the casino's reputation, their are those who are just their making unecessary excuse to why they don't want to pay a particular gambler when looking at those excuse the gambler appears to be free from any form of cheating, but the Casino won't still credit them of their winnings. The part following the ToS and not following help user alot in determining how free they can be when it comes to what they can be accused of or not.