In Amazon's Conditions of Use, the section "License and Access" says the following:
Subject to your compliance with these Conditions of Use and any Service Terms, and your payment of any applicable fees, Amazon or its content providers grant you a limited, non-exclusive, non-transferable, non-sublicensable license to access and make personal and non-commercial use of the Amazon Services.
Also, the section "Your Account" says the following:
You are responsible for maintaining the confidentiality of your account and password and for restricting access to your account, and you agree to accept responsibility for all activities that occur under your account or password. Amazon does sell products for children, but it sells them to adults, who can purchase with a credit card or other permitted payment method. If you are under 18, you may use the Amazon Services only with involvement of a parent or guardian. Parents and guardians may create profiles for teenagers in their Amazon Household.
However, Amazon Household is limited in how many profiles can be created. For example, you can only have two adult (18+) profiles per household. If a family of more than two adults would like to share a single account instead of getting involved with Amazon Household, would they be in violation of Amazon's terms, whether in the section above or elsewhere?
I have just noticed an additional statement of significance in the terms:
By using the Amazon Services, you agree, on behalf of yourself and all members of your household and others who use any Service under your account, to the following conditions.
Might this suggest that the agreement is broad enough to apply not only to one individual but also to the individual's "household" (and maybe even to "others who use any Service under your account")?