I don’t know if this changed, but I could have sworn that every Guru user had the ability to request verification for a lapsed card, regardless of whether they were a Read-only, Author, or Collection Owner.
I then found this Help Center article stating the opposite, that it’s exclusive to just Authors and Collection Owners and wondering if this is new or I just had a lot of Authors in a previous instance. 
No changes here, only the Collection Owner and Author users can request verification.
Read Only users can comment on the Card with or without @ mentioning another user to signal they have a question or have spotted something in need of updating.
I’ve found a Product Feedback post asking Guru to build the ability for Read Only users to unverify Cards, so I’ll merge this question here within it.
All the votes from this idea have been transferred.