It's wage theft, because the law says you owe employees minimum wages by law, and if you aren't paying them that amount, you're stealing the excess from your employees.
The fact that you think you should be allowed to pay people less than the legal requirement is not relevant, the law says you owe people $X, so if you pay them less than X, it is theft.
The problem Lyft and Uber have is the same AirBnB is starting to run into: if your business model is misclassifying things (employees in the lyft/uber case, and hotels in the airbnb case, etc), eventually either (as in NY) court cases will force you to pay what you owe, or as here legislation will be passed to make it so that whatever the company is misclassifying things as, will be covered by the regulations the apply to what they actually are.
Seriously, if your business model is pretending that your specific implementation of X is not the same X covered by existing laws, your implementation will eventually have to comply with the regulations that apply to X.