I think most people would tend to simply dismiss a pop-up warning to not rely solely on the CV, the same way we don’t read data privacy notices on websites or “contents may be hot” warnings on food items.
The problem is not simply that people rely uncritically on the CV. They also reflexively agree with IDs offered by other users. Or they upload observations with no ID at all, not because they have no idea what they saw, but because they don’t know what to enter as an ID (e.g. they assume “bird” or “plant” is so obvious as to be nonsensical).
So I think there’s a larger underlying issue and that is getting people used to thinking about how do I figure out what something is. iNat’s interface doesn’t really encourage this – IDs are suggested by the CV or by other users as if by magic, without making visible the process of arriving at an ID. It also is a fairly passive form of interaction that doesn’t empower users to recognize that maybe they know more about how to classify things than they realized.
What I was thinking of was something more like a set of guided questions that users would answer when uploading an observation before getting the CV suggestions. (Experienced users would have the option to skip this and new users would also be able to skip it by typing in an ID themselves.) For example, they would be first presented with the iconic taxa and asked to select one or choose “I don’t know”. For each of the iconic taxa there would be some relevant additional questions (e.g. “Does it have wings?” “How many legs does it have?” or “Is it a flowering plant”?) that would help narrow the ID down to the rank of order or thereabouts. Only after this would they be told “Our computer algorithm has analyzed the photos and based on your answers and the reference images in our database, we think it could be one of the following.” In addition to the suggestions, there would also be an option “Don’t see any good matches? Choose [order] or enter a taxon of your own”. The idea would be to encourage users to take a more active role in deciding what ID to enter, as well as making it clear that the CV is not all-knowing and they are not required to use the suggestions.