The film and book are set in a dystopian future. Google perhaps can’t get away with something like that now, but in a frightening and hopeless future like the one portrayed in this film, it could happen. People in RPO are obsessed with - or depend on - the OASIS because, apart from being able to have an otherworldly and cool experience, it’s an escape from the bleak work in which they live in. A world where, yes, powerful tech companies like IOI can come after you. It’s believable.
It wouldn't be so bad in the Real Player One world. If the IOI arrest you for subversion or scoring too high on Donkey Kong, they'd jail you in a virtual world. That would be easy to escape from. Just take off the headset and you're free. :P