The lack of normal regulation of binary options brokers was the reason for this.
Suppose 80% of the traders bet that the price of oil will go up. The company looks at this and thinks, "Hell, if only 20% of them win, we'll save a lot of money. A special algorithm takes care of everything. Then the broker just tells the client that the price has closed a little bit lower than the position, what can you do - market risks.
If the client provides proof that the price was indeed higher than he predicted, then the company gives him a link to the contract which states that it uses its own algorithms and the price may be slightly different from the market price.