The CRA and IRS should be the biggest champions of the "sharing economy". Why? Because the sharing economy means the taxable economy.
Uber is solving a problem its founders never intended to solve that it gets no recognition for: untaxed taxi transactions.
Try paying with a credit card in a cab: drivers don't like it and there may be a surcharge. Asking for a receipt results in one (or more) blank receipt slips. The reason for this is that the taxi industry is rife with non-payment of taxes.
Paying with cash means no paper trail and often no income tax (and unreported sales tax). In contrast, when you use Uber to pay for a cab the payment is routed through their credit card processing account and into the driver's bank account. This means that there's an electronic record of the payment that taxation authorities can review. Uber (and similar sharing economy companies) are solving this problem every day without any intention of doing so.
Yet no one gives Uber credit for its role in fighting tax evasion & fraud.
Companies like Uber view taxes as an annoyance because it's added complexity for their payment infrastructure (they didn't set out to solve tax problems). But the result of moving informal/unrecorded transactions into credit card-based, electronic systems is a more readily taxable economy.
Increased efficiency and increased tax enforcement is a win for consumers and society.