This is not the definition of feudalism

Of course it’s not “the definition” of feudalism. But, being paid for the use of something you own is a key aspect of feudalism.

the common theme in it is reciprocal obligations

Suuuure… I’m sure that’s how the feudal lords framed it for their subjects. But, when push came to shove, if you didn’t work the lord’s fields he could have you whipped. If he failed to protect you from brigands you could… complain quietly to the other serfs? The lord would only need to fear aristocrats higher up the food chain than themselves.

Everything that you say is feudal about Amazon, is definitively capitalist

No, it may be happening in an economy where capitalism is one of the main economic systems, but it definitely isn’t capitalism.

Real estate companies are still capitalist even though they deal in real estate.

Take away the company from this example. Is an individual a capitalist if they own land and receive rent from people using that land? How is that different from a feudal lord who owns land and demands rent?