Yeah, just take a look at the financial sector. Your typical big investment bank has insider knowledge of a sizable percentage of the companies in the economy and separately, makes tons of trades. The two businesses are kept separate, no information exchanges between the two groups, no winks and nudges. If they get it wrong, they could go to jail.
If it is possible to create a so-called firewall [0] within banks to avoid unfair advantage via insider trading, it is possible to create a firewall between the platform and seller divisions withing Amazon for a similar effect.
Do you believe that investment banks actually respect the principle of a level playing field? Given the widespread fraud revealed during the 2008 financial crisis, I find that a more plausible scenario is the banks pay lip service to the idea of a level playing field and make a show of instituting a firewall, but in practice the firewall leaks information like a sieve, which the banks ruthlessly exploit for profits. The bigger the bank, the more clients they have, hence the more information they have, hence the higher the chance for insider trading and big profits.
If it is possible to create a so-called firewall [0] within banks to avoid unfair advantage via insider trading, it is possible to create a firewall between the platform and seller divisions withing Amazon for a similar effect.
[0] https://www.investopedia.com/terms/f/firewall.asp