Poparide helps drivers recover costs for trips they are already taking, which generally isn't considered taxable in most Canadian provinces. Check here for the regulations in your province.
However, if you claim driving costs as a business expense with the CRA, you should consult an accountant to avoid "double-dipping."
Carpooling on Poparide differs from ridesharing services like Uber or Lyft, which are considered commercial activities and require GST/HST collection and income declaration.