Gnoming attempts for matched betting don't tend to be too sophisticated. The player will ask their friend or family if they can open an account for them. But rather than creating every account on the loved one's phone, computer or tablet, the multi accounting fraudster is more likely to do it all from one device.
The law is not the same for both parties in many states. In California, it is not illegal to make a bet, but it is illegal to take a bet, or operate as a bookie under California Penal Code Section 337(a).