You're neglecting to consider that other employment opportunities for someone in a given set of circumstances may offer a similarly raw deal, which results in effective exploitation, even if Uber is not solely responsible.
Worse than that, Uber externalizes the cost of commercial vehicle insurance onto the driver. A part-time driver is likely to not carry commercial insurance, due to the expense and to hyperbolic discounting: I'd rather have $X more in my pocket now than protection from a possible lawsuit later. This results in cheap fares at increased personal risk to the driver, who often doesn't fully understand that risk.
Also, these drivers have no ability to negotiate as a group, so they are at a disadvantage against a well-funded corporation that is quickly gaining market power and sets all of these terms.
Worse than that, Uber externalizes the cost of commercial vehicle insurance onto the driver. A part-time driver is likely to not carry commercial insurance, due to the expense and to hyperbolic discounting: I'd rather have $X more in my pocket now than protection from a possible lawsuit later. This results in cheap fares at increased personal risk to the driver, who often doesn't fully understand that risk.
Also, these drivers have no ability to negotiate as a group, so they are at a disadvantage against a well-funded corporation that is quickly gaining market power and sets all of these terms.