Because you didn’t read the technical specs of that service before you purchased it. The information was there and you ignored it. Why do people buy things based on assumptions?

Here is the info you should have read before you bought. They have a page dedicated to this exact topic:

https://www.amazon.com/gp/help/customer/display.html?nodeId=GUVGB3QMQRYRERYW

Of course I like every other human that uses any Service in the internet read the whole Terms and conditions when I signed up and everytime they changed.

I am pretty sure it is illegal in my country to not disclaim such information before you purchase. And it should not be legal anywhere!