Please feel free to implement whatever unfavorable policies you like in your own nations. You are welcome to further drive down your GDP per capita if you’d like. That’s not what the US is though.
If you think this exists for your benefit, please feel free to bask in the illusion of your wild runaway success.
Then, in the EU, you have to factor in fluctuating currency exchange rates and sales tax/VAT set individually by each country. This is another issue altogether.
Online stores should be forced to allow manufacturers to use their sites as free advertising platforms to expose consumers to their products, while incentivizing them to actually complete the transaction someplace else?
Should brick-and-mortar stores not be allowed to offer price matching either?
This is clearly manipulative and is regulated outside the US.
The issue is that when you pay only that basic referral fee, you won't make a lot of sales. You have to pay more to actually make those sales, which amounts to ~46%. Advertising, fulfillment, and other fees. You have to pay for all of this while being required to keep your price "fair," so you have to raise prices on other platforms to stay afloat.
You could just ignore selling on Amazon altogether, but in the US that's rather unrealistic at this point, and they know that.