It has to do with new regulations regarding energy efficiency in various states and countries that came into effect recently. The actual regulations vary from state to state and country to country. Some units build prior to a certain recent date can still be sold, but any new builds must comply with the new regulations.

It's possible the other pre builds you see for sale are older and were assembled prior to these regulations coming into effect.

CA is the vanguard, the other states cite to the CA CEC provisions and incorporate them by reference.  Same as with CA CARB standards.  

All of those states have adopted the much more restrictive Energy efficency standards. California regulators adopted a draconian mandatory energy efficiency regulation for computers and monitors - devices.

California is also trying to TAX retirement from other states and the government even if you never worked there so its not a good idea to retire there thinking your retirement income wont be taxed because you never worked there.

https://www.energy.ca.gov/sites/default/files/2021-04/Computers%20Reg%20Adv%20final.pdf

Its like the European ROHS standards for Lead and other heavy metals.