Again, I agree with Mike's. Nearly all bikes are made in China.
On a brief glance, brands in the Saad link are closer to what is called Chinese imports rather than US brands, and are definitely not "top brands". Though I see them selling Biktrix (a fairly decent though low-cost Canadian brand). Just another online seller - like Upzy maybe?
"US ebike companies" make their bikes in China, contributing merely the designing step, choosing from dozens of already available (in China) components . They have US offices and the most expensive of them have US dealers. Cheaper US brands are closer to purely Chinese imports, not much support from the office, no brick and mortar stores (though you can sometimes buy them in bike shops and places like Walmart), hard to find somebody who would service it, though parts are mostly generic and cheap and can be obtained from many online sources. Ex, I would classify Nakto as a Chinese import and Big Cat USA (on the list in that link) as "close" to Chinese import. It's a grey area here.
Now, whether the massive move of most manufacturing to China was "necessary" or not, it's too late to even talk about things that should've/could've been done (or not done) 30 years ago.