Every contract job I've ever done had a negotiable rate. Obviously in some cases they say 'I can't go higher than this', and then you say no. That's part of any negotiation: The implicit assumption that either party will just decide to end negotiations. That is not part of driving for Uber or Lyft because everyone gets offered the same rate, there's no negotiating up/down. It becomes 'take it or leave it', just like being an employee where once you're hired there is no negotiation involved.

In a few cases my contract negotiations actually involved choosing between hourly or weekly, with differences in effective pay based on overhead for both me and the employer.