Insurance. Uber/airbnb/rover/etc. provide insurance for both parties. To me that's a critical value add - I want to know that if my dog sitter leaves some chocolate around I won't be out a few grand. The more important the task, the more likely I am to stick with an insured party.
The problem is that as far as I can tell, the maid agencies all use independent contractors, so while they will replace my stuff, I see no evidence they will cover the expensive thing.
I do think it is fundamental that an injured worker who was injured on the job is the employers financial responsibility. Anything else creates hugely inefficient externalities and unnecessary human suffering. Worker's compensation law is super important
If you get a worker that is working on a Dog Sitter platform and you've had an appointment or two with them, you're probably going to judge they're OK enough. The insurance is more of a first-time-per-person kind of thing. Same for renting out your house and so on: For the first meeting, yeah it's super important. After that, you'll probably know if you trust them enough to skip the fees.
Example: Say I rent out my house and an electrical fire breaks out. Insurance company says "you were using the premises for commercial purposes at the time of loss and your policy does not cover commercial activity. We won't cover the fire damage." This is a very real possibility you'd find yourself in unless you specifically bought commercial/landlord insurance.
You poor trusting fellow. That's exactly how they get you: pay a few months on time, then stop and live for free until you can evict them. Been there, had it done to me.