I don't think you should blame Amazon for enforcing the MFA that you set up. Allowing you someone to trivially reset the password on an MFA-enabled account would completely defeat the security purpose of MFA. If you've been reading HN for long, I'm sure you've seen stories of how attackers have used famous peoples' personal information to compromise their accounts at various services by requesting password resets. Respecting MFA and requiring a higher bar for password resets is necessary for defending against these attacks. And of course, if you're using both Amazon.com and AWS under one Amazon account (which it sounds like youare), then it would also defeat the security purpose of MFA if you could reset your account password through Amazon.com after setting up an MFA to protect your AWS usage.
I think your conclusion and advice is good. Separate your accounts for different services.
> I've hit an impasse with support, they'll only accept a notarized identity verification form and affidavit to proceed, which isn't that easy or cheap to do outside of the USA.
This should in fact be very cheap most places in the world. Do they not have notaries public in your country?
Generally you just need to sign a legally binding form asserting under penalty of perjury that you are so-and-so, and this is your account. You do this in front of the notary, and they inspect your government ID to confirm it's really you. Then the notary stamps the document to indicate that they've witnessed you signing it, and have inspected your id. Now you're done.
A number of online businesses require this in certain circumstances, and it's something that you can do in about 10 minutes at a store. In the USA, stores like the UPS Store, Kinko's Copies, etc. often have notary services. If you work for a medium-sized company or larger, your company will typically have a notary in its business center who may be willing to notarize personal documents for free. It should be a pretty simple process to complete, if inconvenient.