IOI stayed within the bound of the law most of the time.
The "labor camps" were legal in the books as a form of indentured servitude for debts.
Wilson looked up into the lens of my hallway camera and smiled pleasantly. “Mr. Lynch,” he said. “My name is Michael Wilson, and I’m with the Credit and Collections division of Innovative Online Industries.” He consulted his clipboard. “I’m here because you have failed to make the last three payments on your IOI Visa card, which has an outstanding balance in excess of twenty thousand dollars. Our records also show that you are currently unemployed and have therefore been classified as impecunious. Under current federal law, you are now eligible for mandatory indenturement. You will remain indentured until you have paid your debt to our company in full, along with all applicable interest, processing and late fees, and any other charges or penalties that you incur henceforth."
Ready Player One - 0028
Then later, Wade makes specific reference to how a certain law gave him protection, implying that IOI didn't break the law (most of the time).
At the next station, a bank of machines gave me a complete physical, including a battery of blood tests. (Luckily, the Genetic Privacy Act made it illegal for IOI to sample my DNA.)
Ready Player One - 0029
However, IOI did break the law when trying to kill Wade, which is what Sorento got arrested for at the end of the book.
“This is airing on all of the newsfeeds right now. The feds just took Sorrento in for questioning. They stormed into IOI headquarters and yanked him right out of his haptic chair!”
A video clip began to play. Handheld camera footage showed a team of federal agents leading Sorrento across the lobby of the IOI corporate headquarters. He was still wearing his haptic suit and was shadowed by a gray-haired man in a suit who I assumed was his attorney. Sorrento looked annoyed more than anything, as if this were all just a mild inconvenience. The caption along the bottom of the window read: Top IOI Executive Sorrento Accused of Murder.
“The newsfeeds have been playing clips from the simcap of your chatlink session with Sorrento all day,” Aech said, pausing the clip. “Especially the part where he threatens to kill you and then blows up your aunt’s trailer.”
Ready Player One - 0039
(all emphasis mine)
So, IOI does break the law, but by and large, their activities are legal. The arrests were specific to the various attempted and successful murders of Wade, his aunt, everyone in that stack, and (in the book) the other members of the High Five.