To explain- "they are getting charged $20/month for LR Classic and PS?"
Photography Plan + 20GB storage = US $9.99/month
Photography Plan + TB storage = US $19.99/month
If you only install Lightroom-Classic you will never need more than the 20GB plan provides, or not use at all!.
The extra 1TB storage might only be needed if you plan to use Lightroom Mobile Apps and store photos in the Lightroom Cloud.
Regards. My System: Windows-11, Lightroom-Classic 15.6, Photoshop 27.8, ACR 18.7, Lightroom 9.4, Lr-iOS 10.4.0, Bridge 16.0.3 .