Why are PS4 and PS5 unable to read PS1 or PS2 discs?

Question

They are clearly able to emulate the games based on the PS1 and PS2 games being available on the digital storefront.

Edit: Thank you all for the informative replies.

In: Technology

Answer 1

PS1 and some PS2 disks are based on the CD standard. The drive in a PS4 (and I assume PS5) doesn’t read CDs. Among other things it’s only equipped with lasers for DVD (650nm) and Blu-ray (450nm).