Hi Bernard,
I understand what you are saying, but I still think access=no might be overridden for particular classes of user. The examples given in OpenStreetMap Wiki seem to support this. For example in this entry:

https://wiki.openstreetmap.org/wiki/Key:access#Land-based_transportation

access=no, bus=yes - means that only buses are allowed to enter (for example a road only for buses and forbidden also to pedestrians) 

I know you said that entries in the Wiki might be wrong, but there are numerous entries agreeing. In the access table for a path or track the first entry is “All”: setting this to no generates a tag access=no. I think the important word here is “all”: if only certain classes of user have right of access then access all should not be yes. 

As I said in my last comment, I think this is a matter of interpretation.

Regards,

JB - twospeed