> In your shed example, a builder could contact you and negotiate the price (perhaps the $100 price you set is completely unrealistic).
The argument presupposed that you refuse to negotiate. To say "but you can negotiate" sidesteps the whole thought experiment. You post the job at a fixed price. It's in writing on your posting, "fixed price". A builder accepts it. Or maybe they try to negotiate and you refuse and they do it anyway, or someone else accepts it. Either way someone ends up doing the job at your fixed price. Does the builder now have grounds to sue you for benefits and maybe a pension plan because you don't like haggling?
Anyway I think price negotiation is a bad criterion to use. It is neither necessary nor sufficient to prove anything.
In this shed scenario, if the first 10 builders to come across the ad think it's unrealistic and either ignore the ad or try to negotiate and get rejected, they walk away unscathed and quickly take other higher paying gigs. With Uber, I believe ignoring or rejecting customers is detrimental to your ability to continue finding higher paying customers.
... But not detrimental to your ability to find other ride-sharing apps, or non-app methods of discovering customers...
This seems like a rather different direction of argument. The analogy had a known price before you decide. Allowing you to cancel without penalty wouldn't rate as negotiating anyway. Now you are talking about having to commit to work without knowing what you'll be paid (except in general terms presumably). There are other contract gigs where that happens, as well as full-time employment where that happens.
The argument presupposed that you refuse to negotiate. To say "but you can negotiate" sidesteps the whole thought experiment. You post the job at a fixed price. It's in writing on your posting, "fixed price". A builder accepts it. Or maybe they try to negotiate and you refuse and they do it anyway, or someone else accepts it. Either way someone ends up doing the job at your fixed price. Does the builder now have grounds to sue you for benefits and maybe a pension plan because you don't like haggling?
Anyway I think price negotiation is a bad criterion to use. It is neither necessary nor sufficient to prove anything.