I've no idea why you're getting downvoted, as your comment is spot-on. Currently going through a permitting process for small modification in my yard, and the town is very explicit about what needs a certified engineer's stamp and what does not need it. It is a very specific requirement and specific thing to produce.

If it does not have the official stamp and signature, it is NOT a certified/stamped/approved drawing. End of story.

Perhaps it works differently in different states, but this has been the routine in every state in which I've lived.

the bottom line is that the presumption is that it is NOT an engineering drawing NOR is it certified, unless the certification/stamp/signature is explicit.

Also, thinking about it a second, the stamp/certification/signature is literally the engineer putting their reputation, license, and career on the line over the accuracy of the drawing. No engineer is going to want that to happen as a default operation — it must be explicit.