This is not news yet, but will eventually become so.

Amazon has many many toys, gizmos, kitchen items and hardware bits and pieces they list and sell from Chinese and other eastern sources that are all actually drop shipped by Hong Kong post.  

Hong Kong post is how Amazon can sell hardware bits and pieces by small quantities for prices that range under $5.00 and still make it pay.    The US Post office delivers these items for free, in keeping with treaties and such that should have ended when Hong Kong went back to China.

Issues exist with this system, right now billions of items are hitting the US Post office for delivery before Christmas.   It isn't happening as the overload from the seasonal rush has stopped the containers from unloading in a timely fashion as the US Postal system is totally choked up domestically anyway right now. all the way down to a dead crawl.

Amazon guarantees each shipment, A to Z.   Guess who is taking it in the neck when the shipments DO NOT ARRIVE ON TIME.   Yep, Amazon.   Guess who China is not allowing to charge back the Chinese vendors, yep, you got it .  Amazon.

You cannot buy metric bolts and nuts anywhere but Lowes, Home Depot and Amazon.   There are no more general hardware stores anymore.

This situation is starting to suck, more and more.

Amazon has started rolling back delivery dates to the second week of January in their system, with no notification to the customer.   You can't file a late claim to get your money back (A to Z guarantee) until the new later arrival dates have elapsed.

There are three local lumber yards within 7 miles of me that sell metric, and at least two ACE hardware stores.

Guess you live in a "big store" area

WILCO in Gig Harbor WA has a vast array of metric fasteners, including stainless steel. It's my "Go To" source since I have 2 cars, a truck and 2 motorcycles of Japanese origin. Oh, and 3 Specialized bicycles.