They don't need to avoid the perception of bias because they're free to run their marketplace however they want. They have absolutely no obligation to look out for anybody's interest except for their own.
But, FWIW, it totally makes sense for them to have different rules when the third party merchant fulfills orders. Amazon and merchants selling on their platform have different incentives. Amazon cares a lot about their customer experience and has an extremely long-term perspective on customer satisfaction. Many third party sellers are either 1) incompetent, or 2) actively malicious. As a result, Amazon has to structure incentives accordingly whenever they let a third party seller handle part of the customer interaction.
When you get as big as Amazon is, along with the cushy tax breaks and cozy relationship with government that go along with that size, your decisions and business practices need to come under closer scrutiny, the end.
On a slightly different topic, the fact that the seller said he was held to binding arbitration made me very sad. I am super excited for these bullshit "binding" arbitration clauses to get shot down in court, they need to go.
Funnily enough, I notice the same for intellectually dishonest comments that are _critical_ of big tech companies, or at least certain ones. It seems like the fact that you only notice one side of this dynamic is a bias _you_ should examine within yourself.
I'm sorry but this is not true. There are tons of labor laws, just to give one example, that depend on how many employees a company has.
Further, GP also claims that “being a monopoly” is the only scenario in which size matters, but monopoly power is not about overall company size — it’s about market dominance. You can be a (relatively) small company and still exert complete dominance in a market, and engage in anti-competitive behavior that will attract regulatory scrutiny.
That's only true if they don't wield monopoly power.
Personally, I think there's a very strong argument that they do.
It would be interesting to see to what extent courts agree.
For instance, Amazon holds a significant percentage of online book sales—and, in fact, of online retail sales in general; see one of the sibling comments for references.
See there's two points this comment can be coming from, the first one is as a legal statement, like they don't need to do it because legally speaking there is no way that they could be forced to run their marketplace any way but the way they want, and it seems like that is what you mean - but the fact that governments exist means that nobody is really free to run their market in any way they want. There are always restrictions. And if someone were to think otherwise I would wonder what led them to think that.
The second way is as a moral viewpoint, which is what your next sentence "They have absolutely no obligation to look out for anybody's interest except for their own." also implies (as obligations are often referred to in the context of morality, while in a legal context we requirements are more often referred to - at least in the vernacular).
So which is it? Do you believe there is no way they can be legally bound as to how they run their marketplace, or is it just that you believe there is no moral obligation as to how they should run it (or ethical obligation, I actually prefer the word ethical in this case).
This lawsuit is the equivalent of a consumer goods brand bitching and moaning because a supermarket imposes conditions on them if they want to get valuable shelf real estate.
Trying to acquire a monopoly via these practices is also not allowed.