It’s not a crime per se, but it does open them up to civil litigation. Because it’s a contract of adhesion, where the consumer gains nothing from the additional terms, cannot negotiate the terms prior to acceptance, and is forced into accepting the terms on a take-it-or-leave-it basis.
In order for a contract to be enforceable, both sides need to be able to negotiate the terms, and both sides need to receive something meaningful from said contract.