Forget about private spaces. Age-bias is real. Especially after 35+ when you start to lose hair. WFH does help significantly to fight against age-bias. I hope full remote becomes the norm.
I have repeatedly had to tell recruiters that no, I am not adding a picture and date of birth to my CV.
They were completely baffled by the concept.
[1] https://www.academia.edu/35495485/The_Most_Litigious_Countri...
It is hard to hide an age :)
So either
(a) they want to discriminate (even subconsciously, like thinking 'I can't imagine this face having this experience) or
(b) (which I find more likely) they just want to turn away candidates before investing the 30-45min first call that's meant to establish that the CV and the person actually go together (and the candidate hasn't just made wild shit up).
So "understandable" but undefendable in my eyes.