Almost anyone can become an Uber driver without much effort. Not true for plumbers and HVAC people.
There are so many drivers available they're waiting for your call. Any decent plumbing/HVAC company has a backlog.
All Uber drivers are centralized under one pricing system. Plumbers/HVACs control their own pricing logic. I've never gotten contractor estimates that weren't across a huge range from low to high.
You can never trust a referral unless it's from someone you know that received the service themselves.
Uber vs. plumbing/HVAC is apples and oranges.