The people who make the argument against labor laws like the ones at issue with Uber often do make the same argument against minimum wage laws, or other laws restricting "abusive" contracts.
I know that a lot of right-leaning Americans think that government should stay out of private contracts, but they'd be dead wrong. If the employee was just as powerful as the employer, then the situation would be different.
(1) The existence of the lawsuit means that the generalization serving as the explicit premise here is incorrect.
(2) Without defending Marxist class struggle as a valid or correct framework for addressing reality, the idea that the drivers seem generally satisfied with the arrangement is relevant to whether characterizing it as a Marxist class struggle is necessary may reveal a poor understanding of the entire idea of Marxist class struggle and particularly the role of class consciousness within such a struggle.
People are more important than you're business model.
You can make the same argument against minimum wage, or any other abusive contracts (payday/predatory loans). A lot of time one of the party signing the contract has no other option depending on his situation, that doesn't mean a company/individual should be able to take advantage of his situation and get him in a tough bargain.
Also, not all contract signings are created equal, that's how a lot of companies sneak no-compete's which have been deemed unenforceable many times.