Product Boxes, and Web Sales should show Auto EOS at time of Purchase
What does not help is the large high street stores are still selling models that are getting short on support life without highlighting this.
Example PCWorld have ACER 14 CB3-431 on sale for £179 its Auto EOS is June 2021 - so less than 2 years. Its also available on Amazon for the same price, neither highlight short support life, though at least on Amazon you can see its been for sale for more than three years, but again if you did not know of the Auto Update expiry you would be in the dark.
For the savvy the resources are out there to check so you only buy one with a long support life, the information should be available for all, seeing as they decide the EOS date at build time the boxes should come with EOS date, which could mean some real bargains on kit with 2 years support left on them, or sale prices on those with longer life as retailers make sure they shift them before nobody wants them anymore.
I found out mine hit EOS when I had had it for just shy of five years, in which time it had required a new battery (HP Pavilion with external battery) it had cost £200 and I had not expected it to have lasted much beyond that anyway
Its easy to find the dates - if you know they have set Auto update EOS .... its being obvious to all with clearly marked EOS - like a Best Before Date when you buy food.