In the US it is usually easy to find generic brand sodas in cans. Most large-ish grocery stores have them.

https://www.tomthumb.com/shop/product-details.208010001.html

https://www.kroger.com/p/big-k-cola-soda/0001111049680?

https://www.publix.com/pd/publix-cola/RIO-PCI-106059

https://www.walmart.com/ip/Sam-s-Cola-Soda-Pop-12-fl-oz-24-P...

https://www.heb.com/product-detail/h-e-b-original-cola-7-5-o...

I’ve shopped in the US for a few decades. The store brand soda has always come in aluminum cans (in addition to all the other forms of packaging coke uses).

Also, prices for coke in plastic bottles are also up.

Care to elaborate?